Choptalk, if you want the softest games I'll list the sites in order from softest to toughest. I thought you only wanted an opinion on graphics.
Pacific. Terrible software and single table only, but the softest. Included for completeness only.
Party (and skins). Mediocre software but great games.
Prima network. Good software, good game selection; fairly soft games.
Cryptologic network. Mediocre software, mostly texas holdem, european schedule if you like playing in the afternoon.
Paradise. Used to be the toughest but no more; great game selection very good software.
UltimateBet. Best software, great game selection, tough (but beatable) opposition.
PokerStars. Great software, toughest games; great tournaments, second only to Party in size.
Except for Pacific, those are the ones at which I usually play. There are others like Doylesroom, Truepoker, and Absolute that I occasionally visit, but my schedule is pretty full. I'd play Doylesroom much more if they supported hand histories (and Pokertracker), and went to a 10-player full ring format. Truepoker is too slow for me, but otherwise fine. I have practically given up on Absolute.
I think PokerStars will continue to grow. As they do the games will get softer. Since the reload bonuses there never expire I always deposit enough to max them, and nibble away at them wneh I have nothing else to do.