Depending on your budget, I would buy nothing less than a new Samsung 8000 series LED TV. I recently upgraded from a 46" Sharp Aquos to this new 55" Samsung and the difference is incredible. It also comes in a 46" or 65" version as well.
http://www.samsung.com/us/video/tvs/UN55C8000XFXZA
It has, by far, the best picture I have ever seen on any television, and I looked for a new TV for almost a year (was waiting on 3D sets). I have not used the 3D function yet, but since it seems to be the new standard I didn't want to buy a TV that was not 3D capable. I did a lot of research beforehand, and from what I gathered, the 9000 series (the only model line above the 8000 series) adds nothing but a fancy touch-screen remote and $2000 on top of the price of the 8000 series sets. Yes, I realize there are differences between them, but they appear to be so unnoticeable that it didn't make it worth the extra $2000-for me at least.
Even the older, non-LED Samsungs are nice TV's with excellent picture quality, and the company always seems to be at the top as far as picture/product quality. I will never buy anything but Samsung's from now on, but to each his own.
I also looked at Plasmas, but the picture quality/color did not impress me at all. Everybody has their own opinions, but I would NEVER buy a plasma, JMO of course.
Whatever you do, DO NOT buy anything less than a 1080p HDTV. 720p televisions are nothing but a waste of money, and I thought that most companies quit making them. I can assure you that you WILL regret it if you buy a 720p HDTV.
Good luck in your search.:thumbsup: