In reply to Bill Curry.

Which one is the best? That would depend on what your particular needs are and how well the three options meet them. If I were in your shoes I would put together two lists, 'must have features' and 'would be nice' and then go through the 3 alternatives and see how well they stack up. Keep in mind that BuddyPress has tonnes of plugins which can extend its core functions and it has been architectured that way from the start.

All in all, I'm glad to see more competition in this area of wordpress development.