I'm a big tech nerd and when it comes to TV's my family is about to to tie me up and gag me. ;D I have three HDTVs and sold another I had last year. So far _B_u_r_l_e_y_ has given great advise. On terms of cables he is right on buy your cables and mounts from monoprice!! You will save a fortune and will not loose any picture quality. I also have one of their wall mounts and for $70 after shipping I got at a great swivel and tilting mount. I'd also like to point out that 90% of all HDTVs now have a QAM tuner. What does that mean? Well it means you can plug in your cable and get the non scrambled digital channels. What does that mean? Well it means you can get you local HD stations without a antenna!!!! The cable companies are required by the FCC to pass the local stations without any encrypting of the signal. So get a splitter and run a feed to the TV and Cable box. You will probably get a tons of other channels as well. Usually 1-72 of analog SD channels and many digital music channels in my case. With all that said I seriously recommend Directv for any new HD buyer. They often have special promos at best buy for new HDTV buyers who are interested in switching. The NFL Sunday Ticket deal is also hard to beat.
Now as far as TV goes you have to determine a budget. There is no doubt Sony, Samsung and Pioneer (Kuro plasmas) are the best three brands for PQ out there. They also cost more then the others. I would first consider the size and display type you want before brand.
LCDs are best for bright rooms and are great if you intend to use it for computer use as well (like I do). While Plasmas are considered by most to offer the best PQ of all the display types for dark rooms (not counting CRTtubes). They use to suffer from burn in issues and not be very bright. This led to LCD selling better because in a bright show room the LCD would look better. When in reality a Plasma is usually better in a living room setting. They also have great viewing angles compared to LCD and DLP. What I mean by this is you can walk all around the room and even from a extreme side view the Plasma will still look fantastic. Where DLP and LCD will either wash out or darken when you begin too look at it from a angle. Plasmas have made allot of strives this last year in size and price and as long as you watch burn in it's what I'd recommend.
Now as far as DLP goes thet are probably you best bang for the buck when it comes to screen size. They also offer great color and blacks when viewed from straight on. The bads are bad viewing angles, screen door effect, and bulb replacement costs. I've went over viewing angles so I'll go over screen door effect. IMHO it's what makes DLP to be not as sharp as LCD and plasmas displays. It's very hard to describe until you see it but the display tech just looks different and I prefer my LCD over my DLP because of it. The real bad thing about DLP is the bulb replacement cost. Most DLPs have had about a 5,000 hour life at most before you have to replace the bulb and that runs about 200-250$. The good news is that they have came out with LED DLPs and they are suppose to last allot longer then 5,000 hours. They needed to do this because most Plasmas and LCDs are rated for 30,000-50,000 hours.
Now on to brands IMHO if I could buy one TV today for under three grand I'd buy a Samsung 120hrz LCD period!! I love them and they are the clearest thing I've ever seen and they can ruin other TVs for you. I'm serious they are that f****** good. That said most peoples budget aren't $3,000 either. So what you should say to yourself ask how much money you have for this and how big you want your set. Then read reviews at Cnet and posts at AVS forums. So if you find you can afford to buy a 50 inch and have enough to buy a Sony or Samsung then do it. However if buying a Sony or Samsung forces you to downsize to a 42inch I would look into buying a Vizio. They have did a amazing job of balancing performance and cost for consumers. They also have a very good warranty in case anything happens unexpected. I have a very high opinion of Vizio and what they are doing. There is no doubt the high end Samsung, and Sony displays will look slightly better when they are the same size but when you factor price you can in some cases get a 50inch Vizio Plasma for the price of what a Sony 32inch would cost you. So what would you rather have?? My dad is about to get a 50inch Vizio plasma that come with wireless surround sound for $1200 and that a amazing value!! BTW don't over look Sams Club and Costco because they offer great prices and a great return policy.
When it comes to resolution I've gotten to a point where I tell family and friends for anything under 47inch just make sure it's at least 1280x720(Some low end Plasmas are 1024x768). Most people can't see the difference, but some like myself with good vision can. The smaller the set gets the harder it is to see the difference between the resolutions. Your more likely to see compression issues from channels and service providers then you are to see the PQ differences between 720p and 1080i or p.