About the only knock I have on Bilal is level of competition (can say that about a bunch of dudes), his shot is a little slow, and he is skinny. As far as mystery boxes go I feel pretty good on that one.
Flip > GG
Like with Flip he has good hands (on offense and defense), he makes good passes, he has some good moves around the basket (doesn't always finish) so if he shoots the ball well he is an nba big... maybe not a starter.
I get the idea of GG but he's almost like a reclamation project. Not starting from the ground up... you are tearing down some of the **** then starting from the ground up. If GG is successful I think it will be as a second draft guy. Call it immaturity or bad attitude... it won't just disappear usually until they have hit a wall somewhere. Give him millions and see if that helps him grow up... that seems to always work. I'll bet he has a career arc like Whiteside, Wood, etc. Sucks until he is on the cusp of being out of the league then he turns it around.
In 2-3 years go get GG from whatever team drafted him. That is my recommendation.