Giannis is such a unique player. How many players can be in a dominant position against their defender when they are backing up? Honestly, the best way to defend Giannis' drives may be to just guess which side he is going to Euro step because no big defender is fast enough to react to it. I have no idea how to stop him on the offensive boards. He is too strong to box out, too long and athletic to out jump. If he starts shooting 75% from the line, Hack-a-Giannis is not going to work either. The only way to defend Giannis one-on-one is to convince him to shoot 3's.
That said, when Giannis is bringing the ball up, he does make himself defendable. The other team can set up on defense facing Giannis, and just sag into the paint and double team him on the drives. That is harder to do when he gets the ball on a reversal.
I still think the Bucks are at their best offensively with Lopez inside, posting up, or waiting for the dump off/alley oop from Giannis or Holiday on the drive. This creates space for Middleton and Connaughton/Tucker to shoot 3's off kick out passes.