Flip a coin. The TVs mentioned are all good. Personally I'm not a Samsung fan. I like Sony, but that's my 2-cents. The guy sitting next to me likes Samsung and the other guy likes Toshiba. You need to go to a retailer and view them all yourself. Play with the remotes to see how the menu is on each TV and what kind of controls they give for adjusting the picture.
I've been putting it off for a while now, but I'd really like to get a 1080p 42 inch lcd. I know that samsung, toshiba, sharp, and sony all make models in this range, but I don't know how to evalute them. I know about resolution, contrast, and size, but how do you measure color reproduction? I'm going to use it with a ps3 for games and movies, as well as for watching high def tv. I may also connect my PC, so I'd like to set to display 1080p right from the pc input.
I am concerned about the bands mentioned in the Sharp. The Toshiba, Sony, and Samsung all got great reviews, and no downsides were given with the Toshiba. If possible I'd like to have a set that has deep blacks and accurate color reproduction. You can see the reviews of the Sony, Samsung, and Toshiba here: