I'd go with Wiggins.
As much as I like Avery, I let him go (S&T maybe) and Wiggins is my starting SG in the Fall.
The reason I take Wiggins over Embiid comes down to marginal difference at their position.
If healthy, I project Embiid to be, eventually, at least a top 10 center in the NBA, with a decent chance of maybe cracking the 'top 5' at his position. That will likely take several years to realize. Keep in mind, that next year's draft alone may have 2-3 centers who may be better prospects than Embiid.
Wiggins, imho, will probably be in the discussion for top 5 at SG by the end of next year. He won't BE there yet, but he'll be knocking on the door. And it won't be long before he's in the discussion for the top spot at his position.
Shooting guards who are 6' 8", with a 7' wingspan, who move like the wind, can shoot for average from anywhere on the court, can play above the rim and who can guard 4 positions are not just rare. They don't exist. He is a game-changer at his position.
I also think that Wiggins is an ideal floor mate for Rondo since he is not a ball-dominant SG like a Kobe or a Harden.
Between the two of them, Rondo and Wiggins would provide just a hair under 14 feet of wingspan. Add Jeff Green on the perimeter and that is 21 feet of wingspan in three very athletic defenders.
Unfortunately, Wiggins is likely to end up as a Buck or a Sixer. But I'll still be happy with Embiid or Parker, if we at least get in the top 3.