How do I gracefully accept one offer over another within the same company?
cperciva: I think the phrase "I think I'd fit better with team #1" is probably what you're looking for.  When you get right down to it, "fit better with" just means "I made the decision based on personal factors", but the phrase implies that you're considering how said personal factors would influence your ability to do useful/good work... which is at least slightly deeper than merely picking the people you like the most.