i would pick starwood over hyatt & hilton....
starwood has more properties than hyatt & have great benefits for their top tier members....
hyatt would be my second choice....while they have limited number of properties (as compared to spg & hh), they do have great promos....
hilton would be at the bottom of my list for a number of reasons which i don't want to get into over here....their program has just been going downhill....