ATV offroad fury 1 is clearly the best one to come out so far. I still have more fun playing it than all the others.
Right now, i play atv offroad fury 1 the most. But of all time, id have to say super mario. For multiplayer Halo1 and 2.
The best playstation 2 multiplayer/fps game of all time, Warhammer 40,000 fire warrior. The bad part about that game is nobody knows about it, and its prolly the best fps game for ps2, kinda repitive though. It has online capabilty but no one has ever been on since i bought it and have been checking.