getting new games for the xbox

so according to what im reading the bioware games are the ones worth playing. so i guess that could possibly be a direction i could move in as far as xbox 360 purchases. there's two that're basically sticking out so far, mass effect and knights of the old republic. both scifi and both rpgs. but there's got to be more worth selecting from. there's one that stands out in mind, halo 3. i've already played through the halo series up to that point. so that'd be a reason not to go down that road again. but they were enjoyable games. however i did play the fuc k out of them, so i might be halo-d out.