Night float is about getting the work done, and not so much about learning. You lose a month of elective, typically. You miss all the conferences. Overnight call is more physically taxing, but is sometimes better. It is amazing how much of a difference there is between q3, q4 and q5+ schedules. I think call spread out over the entire residency is ideal (hopefully at least q5). If the schedule is not insane, call can actually be fun. I would be wary of residencies with lest than 4 per class, or numerous hospitals to cover.