You will deal with a larger volume of people at Sbux, but your interactions will be mostly incredibly brief. So factor that in. Probably annoying clients both places.
But my biggest advice as someone who has worked in similar places, is pick the one with the best, most professional and organized manager. Not the friendliest or nicest manager, the best one. You want someone who gets schedules out on time, who will protect employees from nasty customers or stupid corporate policies when necessary, who will be professional and just do their job, and not worry about being friends with everyone. If you can find a manager like that, either place can be perfectly tolerable, even nice.