If you like your legs a bit thick and long with a strong look, then it would have to be the Greater Yellowlegs. If you like your legs a bit on the thin side, petite with a dainty look, then it would have to be the Lesser Yellowlegs. Here is a nice comparison shot, which sometimes are not so clear when looking at both species in the field. Me, I am not picky, I like em both :)
Greater and Lesser Yellowlegs. Do I really need to indicate which is which?