My favorite online game is CABAL, but I also play, plants vs. zombies and angry birds if I have spare time.
Bast oneline games is Wonderoutt, Curve Ball, Asleep Walking, Turkey Liberation Front 3, Cat with Bow Golf, Perfect Hoopz 2 and so one.
Now-a-days i am playing Angry Bird and I am feeling that I like that game. So I guess Angry Bird is the best online game for me now.