Any sized board will work with most any sized person, it really just depends upon your preferences and budget. However, we do have a weight limits:
Small: max. 180 lbs.
Medium: max. 220 lbs.
Large: max. 250 lbs.
Our testers start out liking the smaller boards at first but the more they use and the longer they stand the more they prefer the larger board with the straight back edge for stretching calves and tipping the board up. I like the large best, and I'm 5'8". Try one of the large and one of the small — Kids love them, too.