FarmVille is really nice and i was really addicted to it sometime back but i guess it just take up all your time and there is so much to do in it now.
I played a lot in facebook. I have recently three games. Backyard monster, desktop defender and zynga poker. Facebook is so cool.
my best face book game is happy aquarium , i love those fishes and tank cleaning system , feeding on timely basis , its like we take care of a life with interest.love playing that game..
I'll vote for Cityville. I enjoy the game because it's a mix of farmville and other games. THough, Farmville is my favorite before when it became the most popular game.