I play power chords using first and third, I initially played with my fourth, but changed that soon, I incorporate alot of power chords with additional notes into my playing, so I like to use my third finger, so that I can add in a higher note(either a flat 6th or a 6th or a seventh, even an octave) I usually add this not for certain beats and lift it for others...I quite like the effect it creates(obviously which note you add depends on what chord you are playing and in what key you are playing)...

But generally, hand size matters very little...the best bassist I know has tiny hands...and he is playing on a Yamaha John Pattituci 6string bass, which has a neck as thick as a tree