Well from my perspective, it depends on a few other things. Do you have a Brand Preference? Resolution (1080/720)? Refresh rate (60 hz/120hz/600hz)? and finally LCD LED or Plasma?
For around $800 You can get a nice Sony Bravia 40" Ex500 (1080p/120hz). Or Probably go with Samsung and a comprable model. Those are the 2 BEST brands when It comes to TV's.
Otherwise, you could go for a lesser known brand, perhaps a Vizio/Insignia/ or something in the like. Probably get something around the same specs but maybe a little less in the quality department. It really all depends on your own preference. If there's one thing I can recommend, when you go shopping for it, step back and just look at it. Often times there'll be a picture that you may like best for yourself.
I promise im not pulling all of this out of my @$$, haha. I work at a Best Buy as a Home Theater Salesman, but I hope this helps Dude..