Definitely not BOS - loads have been miserable.
My suggestion is MSP, for a different reason - of the three, it's the longest flight, which offers you the most potential opportunity to sleep. Dinner service takes 1.5-2 hours even in economy, and on the <7 hr BOS flight that's barely enough time to conk out asleep before you're woken up again for the pre-arrival breakfast. MSP clocks in at a much healthier 8:30 that offers you a reasonable chance of getting some shuteye. (And enjoying the BE cabin if you do happen to win the lottery.)