Play the game that...
... is the most fun. No point in playing a game if it is not fun after all.
... lets you grow in someway. Perhaps interaction in some context or what not, or experiment and try something new.
... Um, or the one with the best eye candy I guess...
... Or perhaps the game play that lets you zone out. (Racing games work well for that; Is it any wonder why I don't drive? lol)