This depends on the dynamics of the song, but generally, for good rhythm playing, especially with bluegrass strumming, is to accentuate the bass, and brush the high notes in the chord. You don't want to attack all of the strings equally hard, a good sounding chord will sound the bass, with the treble lightly. This is a strumming dynamic that is hard to achieve easily, it requires a lot of practice. I've heard guitar players just strum the snot out of a chord, and it sounds like crap. A good strumming dynamic always accentuates the bass in the chord.
