The Bucks have a very bright future ahead of them, so your only job is to allow the players to develop alongside one another.
In order to do so you'll need lots and lots of cap space. Jabari Parker, Malcolm Brogdon and Thon Maker are your three starters that'll be worthy of extensions in the next seasons.
That's why Henson and Dellavedova should go. The first is your third center, but the second is your back-up point guard, which might seem problematic. Still, since Giannis Antetokounmpo is the one handling the playmaking duties, you can solve the issue simply by making sure that either he or Brogdon are on the court throughout 48 minutes of gametime. Harris can get some minutes as well.