I really think the Bucks should make sure to keep Sandro Mamukelashvili.
Right now he might be a good regular season option, but I think he has a lot of potential with the way bigs are used in the NBA these days.
Ibaka and Lopez are no spring chickens, so some younger depth is needed.

Full disclosure, I wanted the Bucks to pick him as I liked his game at Seton Hall.