Minion Mayhem isn't really a crowd eater. Sure, it'll be popular, but the capacity is lacking - reminiscent of The Simpsons. I think Waterworld should stay for the first few years of Potter's stay to draw some crowds in, and same with SES (whether or not it's improved - it's really popular).
I'm a fan of rides that use the efficient loading system seen in Forbidden Journey, Transformers, and a few Disney rides (ride vehicles are always moving, walk on large conveyor belts, etc.). You get in, pull down the bar, and ride. You get out of the ride vehicle, and exit. Everything's super snappy, and it proves useful on peak days.