If you can get some more money OLED will be the best no doubt, although the technology is young, so I would wait for another generation anyway for them to iron out the early issues.
I wouldn't bother with 4K yet, unless it just happens to be in a TV you want, there is simply very little native resolution content, and it doesn't look like it's gonna dramatically change soon.
I would go for a LED TV. Currently for gaming I would say the latest generation of Sony Bravia W8 is the best, exceeds others in very important input lag and has great picture quality. If not that one, keep checking which set has good (low) input lag, black levels, dimming solutions etc. With 3k$ you can't really go wrong with Sony, Panasonic or Samsung TVs, they simply don't go below some level of quality for that price.
As for the size, it depends on what space you have, I'm yet to meet someone who complains that their TV is too big.
So it is happening...PS4 preorder.
Greatness Awaits!
