I've heard horror stories of boards who either interfere heavily with the property management staff or are completely absent. The working relationship between a condo board and the property management company is just as, if not more, important than the property management company itself.
Really depends what you're looking for. We recently switched and got proposals from eight different companies; we then interviewed four. Make a list of your "must haves" and see who matches that. Look at the qualifications of the people they hire. Look at the support they provide those people.