I agree on Parker; I think he will be an All-Star caliber player, but I don't think he has the same ceiling as the other 2. Parker isn't going to play a lick of defense, but he's going to be able to fill it up right away and I'd be shocked if he wasn't the rookie with the highest PPG next year (especially if he falls, as expected, to Philly)
It really comes down to Wiggins & Embiid, I won't be upset with either to be honest. They both fill a huge hole (athletic SF who can run the court, attack the hoop, and defend or the modern era post presence). I think our team "needs" the post player more as Varejao hasn't stayed healthy and is 32 and the rest of our post is a gluttony of PF's (Hawes, Thompson, Zeller, Bennett, etc.)
This draft is deep; I feel we can get a strong SF in the early 2nd. I doubt KJ McDaniels from Clemson drops but if he does he'd be a great fit. Here is a mock draft site that lists some pretty solid talent deep into the draft
http://nbadraft.net/2014mock_draft