If you can pick Embiid, you should do it. I think Parker is better right now, but the NBA is a totally different animal. Embiid and Wiggins will look better in the pros than in the NCAA, and if they get to play with a decent PG, wow.
Wiggins and Parker might still end up as better players than Embiid (even Exum or another guy), but if you can get a generational talent at center you don't let him slip. Forget about positional need or personal bias, if you have a big man who can affect the game on both ends, you just need a PG (and we have one of the best), and scoring from the wings. Miami has that (PG - LeBroid, wing- Karate Hamster and the 3-point band, Big - Bosh), and they do pretty well. Imagine a real dominant big like Embiid with a crafty playmaker like Rondo. Add some good (not great) players and you have a contender.
We're not getting a top-5 pick, though. But if we can draft two out of Saric/James Young/Cauley-Stein, I'll be very pleased.