Come on man, the best one is the biggest one, you know this. :P

Well, OK, not really.

I assume you're running a 50" LCD TV? When I was monitor searching, a couple of my friends were also searching and decided to go this route. That was fortunate for me because I was able to go see theirs and....frankly...I wasn't impressed. They are running 1080p (1920x1080) which is all you need atm for TV, but is woefully inadequate for a 50" monitor sitting right in front of you. Not only was the picture pixelated as can be, but the color saturation was no where near as good as the computer monitors I'd been using.

All this lead me to choose a 30" dell monitor, and I've never regretted the decision once. You can see in my sig how I lay out my toons, and it works great. You can also consider the way Rob mentions above, and this is the way to go if you want to run the same aspect ratio for them (which you do if you use keyclone and its PiP). My problem is that when I run them like that, with the correct aspect, the clients are too small. Plus using the keyclone PiP can take up to 5+ second to switch in my scenario (not exactly sure why, but probably just because of the size of the viewports) so I can't really use it in an emergency condition. :/

I think the ideal scenario for me would be a 30" dell, with a 22" on each side turned 90 degrees. Main toon on the 30, two clones on each 22. Plus you could use the 22" as each desktop space when you weren't wowing.