Important Specs Size – Measured from opposite corners, this is the biggest factor in price of a TV Native Contrast Ratio – The best contrast a display can produce between its whitest white and darkest black at a given instant. A great way to test this is a starfield scene…how white can the stars be versus the blackness of space at the same time? Remember: a high contrast ratio is still shitty if the darkest black it can display is light grey. Dynamic Contrast Ratio – Bullshit. I put this up here because it’s often quoted, but this is a meaningless number. It refers to how black a COMPLETELY black screen can be versus the whiteness of a COMPLETELY white screen. How often do you watch a completely black screen? Exactly. Check the bottom of this article for a good write up on the uselessness of native/dynamic contrast ratios. Display Resolution – 480i used to be the only resolution offered. DVDs made 480p possible if your TV could handle it. HDTV defined the 720p, 1080i, and 1080p standards. A chart at the bottom clarifies what resolution you need, but generally speaking if you’re under 50” a 720p TV is fine. But 1080p is not usually much more expensive either. Deep Color/x.v.Color – These features are being tossed around right now, but at this point in time virtually nothing actually implements them. So while they’re nice to have for the future, don’t make a decision based on them. Viewing Angle – Another bullshit figure. You can “view” a TV from any angle, so LCD manufacturers list angles up to 178 degrees. But your LCD will look substantially worse viewed off angle. 120/240 Hz – This can refer to two different things. In one sense it refers to a feature newer LCDs have that uses a faster refresh rate to avoid the classic motion blur problem. However, it is often combined with features that remove “judder” from movies. This judder is a result of the movies being filmed at 24 fps. Some people love anti-judder, but others hate it and turn it off. DO NOT buy a 120 Hz TV that doesn’t allow you to turn this feature off unless you are absolutely sure you like it. Additionally, here is an article expanding on this spec. Inputs - The importance of a TVs inputs will vary based on whether or not you are plugging everything into an A/V receiver. In this day and age, any HDTV should have at least two HDMI inputs, at least one component input, at least one composite input, and maybe a digital coax or optical input. Some manufacturers include inputs on the side as well as the back. 3DTV - Pretty self-explanatory, with the exception of DLP people. All the new 3DTV LCD/Plasmas work fine out of the box. However, the checkerboard standard that was adopted years ago by the DLP manufacturers is not what made the final cut in 3D. What this means is that if you have a 3D-Ready DLP, you are most likely going to have to buy an adapter. These are often sold in a kit with glasses (I think I've seen one for the Mitsubishi sets at $400 with two glasses included).
2/23/2010 Edit (spoilered because as of 3/1/2011 I'm not sure how relevant this is anymore):
According to this HDGuru article, your current surround sound receiver will not be able to pass HDMI video to your 3DTV. End of story. There are VERY FEW 3D-ready surround sound receivers out yet (though some have been announced). And as the article states there is only ONE 3D-BluRay that can output video and audio over two separate HDMI outs. What this means is that if you get a 3DTV and you currently route your sources through a receiver, your options are to either A) buy a new 3D-ready receiver or plug all the video of your sources directly into your TV and plug the audio to the receiver using optical cables (meaning no Dolby-HD or DTS-MA).
Types of TV Rear Projection DLP Description
This is the legacy system, the only real non-flatpanel display still in existence. Amazingly, it still holds its own very well. These TVs will give you huge screen size (most range from 55-72”) at much more affordable budget. For the best quality, you want to look for LED DLP TVs, which will be lighter, smaller, and consume less power while providing greater image quality. Most importantly, the LED DLPs remove the need for bulb replacement that plagued older models.
Big screens at a cheap price
Generally avoids motion blur
Uses less power than plasmas
Can provide great color
Ignoring bulb replacement, no shelf life (LCDs and Plasmas both rated for a certain amount of hours)
Generally speaking, cannot be wall mounted
May have fan noise
Bulb replacement on older non-LED models
Some notice a "rainbow" effect
Blacks generally won’t compete with mid- and high-end plasmas and LED-backlit LCDs
Mitsubishi is the only one still in this market
The most common tech on the market day, LCDs are known for weighing less than plasma TVs and for consuming less power. Wikipedia can better describe the backing technology than I can. These TVs range in price from absurdly cheap to prohibitively expensive. In general, price differences between TVs of similar size are justified by color accuracy, how well the panel can render quick motion, thickness, and the all-important black level.
There are three main techs of LCD. The first is the "legacy" LCD, which uses a CCFL backlight. These TVs are becoming harder to find every year. The most common LCD tech out there is edge-lit LED. These TVs use LED lighting along the side of the screen (similar to many laptops). This allows the TVs to use less power, become absurdly thin, and still produce a relatively good picture. However, the obvious uniformity issues can come into play when you are lighting from the edges. Each brand typically has one super-high-end line of LED using "local-dimming". Here there are LED "zones" throughout the TV that can be turned on or off depending on what is needed at any given time. These TVs have the best picture of all LCD TVs. Be wary of deals from off-brands on local-dimming...the quality of these TVs is directly tied to how many zones are available. Additionally, the dynamic black level rating is even more useless in this case because the TV will simply turn off all of its lights for the dark part of the test.
Lighter weight and less power-hungry than Plasma
Can be viewed in brightly-lit rooms
Broader size ranges (smaller plasmas have mostly been discontinued)
Motion blur (mostly resolved, see below)
Black levels are still improving, but usually won't match plasma at an equivalent price point (and top-end plasma will still win over top-end LED)
Viewing angle – even top sets suffer when viewed at any angle other than center (much less a problem than it used to be though)
High-end price - in most cases, the best LCD is pricier than other premium sets
Samsung, Sony, Sharp, LG, Toshiba, Vizio
Plasma technology is based on inert gases trapped behind two layers of glass. Plasmas are renown for their spectacular image quality as well as higher power consumption and greater weights. They also struggle to shake negative public perception caused by their early burn-in issues (see farther down this post). The technology has made a strong showing for itself since the 2008 financial because of the cheaper prices of larger high-quality sets and a growing consumer awareness that its issues have been solved. The differences in price between plasmas are usually based on panel thickness and color accuracy/black levels.
Good at all viewing angles
The best possible blacks on the market
Doesn’t need the 120/240Hz coping systems for motion that LCD needs
Larger possible screens at "realistic" prices
Price – in general, plasmas will cost less than LCDs of equal size/quality
NOT Burn-in (discussed more below)
Heavy and power-hungry
Mainly belongs in a light-controlled room
Possible degredation over time and significant use (see edit directly below)
3/1/11 Edit: One thing you may find in researching this technology is that it degrades over time. This is a valid concern when laying down a bunch of money for a TV. The short version is that tons of reading on the subject has convinced me that this is not a concern to be worried about. And usually when someone is steadfastly refusing to budge from this being a dealbreaking-issue, I find that their primary justification is the morons that infest AVSForums. But the people in there who really know what they're talking about, the people who have a longstanding proven history of testing and calibrating TVs, will not harp on this. More spoilered:
This all basically started in late 2009. Over time plasma TVs are configured to make slight adjustments to their voltages. I'm not going to pretend to be an electrical engineer who knows the detailed background of this, but the layman's version is that this will result in the black level of the TV rising over time. This is generally imperceptible and since then reviewers such as CNet have been punishing plasma TVs for longer time periods and updating their reviews with the results (usually this does not change their score because as I said, it isn't noticeable).
Unfortunately Panasonic fucked this up pretty badly in 2009. Most of their models that year made too drastic a change in the voltage somewhere between 1000-1500 hours of use. This resulted in the lowest black level doubling, and that definitely was noticeable. In typical corporate fashion, the farthest Panasonic went was a press statement that essentially read "Our TVs are awesome. But the black level rises. We didn't screw up. But next year's TVs won't do this." In any event they were true to their word, the 2010 plasma models did not rise noticeable amounts over anything remotely resembling typical use. But once you screw up like this long memories take root.
The Great Debate: LCD vs. Plasma
This battle is now mostly the result of the early handicaps of each technology. Plasmas were infamous for their burn-in problems, in which a TV would become permanently stained by an image that had been left on the screen too long, such as a network TV logo or the black bars from a widescreen movie. LCDs were known for being horrible if you weren't sitting directly in front of them, as well as having difficulty dealing with quick motion in sports, action movies, games, etc. The next few bullets are very much my opinion, but I think if you look around reputable review sources you'll see these comments borne out.
Plasma Burn-In is no longer a problem. No, I don't want to hear about your friend who like, watched twenty minutes of mean girls and totally got burn-in. No. I actually wanted to put this up early in the year, but didn't have enough reputable information to justify it. You will have to deliberately try to hurt your TV to cause any kind of burn-in. If you're super paranoid (like me), treat your plasma nice by avoiding static images during a 100-hour break-in. Or don't. If you want to hear about the abuse I've done to my own plasma, feel free to PM me.
LCD motion is also no longer a major issue, provided you're buying a 120Hz panel. Of course, many people never thought there was an issue with 60Hz, and if you're one of those people then you don't need to worry about this anyways. For most people, LCDs with 120Hz and MOTION INTERPOLATION TURNED OFF will not notice a difference between LCD and Plasma.
LCDs still suck off angle. Not as badly as they used to, and probably not a deal breaker for many, but they do.
Plasmas still suck down way more power than LCDs and weigh more.
It still takes $3000+ high-end LCDs to beat the best $1500 plasmas. This price disparity is often expressed in smaller amounts at the lower and middle-end sets as well.
What's the takeaway? There are two. Number one, don't worry about bullshit on EITHER tech. Don't be scared away from buying that plasma because you own an Xbox 360. Don't skip on that LCD because you have the NFL Ticket on DirecTV. Buy a size and quality that fits your budget. I will objectively suggest that often times in the current price market that will be a plasma.
Finding The Best Price
Amazon (and in some cases Newegg) will be your friend here. You can get massive discounts below what typical consumer stores will charge. Sometimes open-box deals are a good way to go, though I’ve noticed that Best Buy open box discounts are usually not worth it. Make sure as you browse online that you check whether a posted price includes shipping…these things get HEAVY. Additionally, make sure you know what warranty you are getting. Some of the cheaper online stores (and Ebay) aren't approved distributors for a particular brand. In these cases, a TV will NOT be covered by a manufacturer's warranty. Don't be fooled either...I've seen a bunch of these sites list "US Warranty" as being included in the purchase. This does not mean manufacturer! It means they're using a third party warranty service, and can refer to any service or the actual company USWarranty, which I've seen bad reports about.
This HDGuru article does the best job ever explaining why looking at TVs in-store is of questionable benefit when making a purchase. In addition to turning their TVs onto "torch" settings, the lighting makes a big difference. The store can still be great to see if the MOTION of the set is up to par (particularly important for LCDs). But in many ways word-of-mouth from AVSForum owner threads can be far more useful than personal experience at Best Buy.
When looking at TVs online, you should treat a TV's listed specifications with a grain of salt, even on sites like Amazon and Newegg. I've noted several times where secondary features or even contrast ratios get confused across lines (for example, a Samsung C630 and a C650 might have some errors between them). And a lot of times features won't be listed (analog inputs, etc). Always check the manufacturer site for real specifications, and ensure that the TV that arrives at your door meets those specifications.
Subnote: Why are there so many models for the same brand that have similar numbers and identical specs?
A lot of these models exist solely for the purpose of thwarting price matching. They'll be minutely different (like one extra random input port or some BS feature). If store A is carrying the mainline model (say a Samsung 650) while store B is carrying one of the offshoots (like a 630 or something), neither store is obligated to price match the other because the models are different. While this isn't a hard-fast rule, generally if the manufacturer is reporting identical picture specs (contrast ratio, response time, etc), while the numbers are meaningless their equality tells you that it's the same panel with just a couple small extras added/removed.