I would definitely say Costco too.....have had great experiences buying electronics from them including one that had to be returned and it was easy as all can be.
The big thing you need to look at is your budget?
Had a buddy who just bought an LG LED that was roughly 46" a couple of weeks back. Just watched the Belmont Stakes and then the hockey game last Saturday on it and the picture was outstanding.
You definitely want 1080P (don't even think you can get lower than that now) and if you like to watch sports get the best refresh rate your budget will allow. I think my buddy's is 120 refresh rate and it is great. This was a secondary TV and he was just looking for something reasonably priced.
The LED screens are great and if I was in the market right now I would be getting the same TV my buddy bought.
I should add too......the pictures now are SO good there is not as much parody between brands at the various price levels. Yes.....a $2000 Sharp Aqueos Smart TV is going to be better picture than a $600 LG.....but the technology is so good now that each company comes out with products at the various price points. For my money....LG, Sharp, Samsung or Panasonic.