Out of the 'top three' prospects I'd have to go Wiggins - no brainer for me.
Parker is already a so-so defender even at the college level. Put him up against NBA level athletes / talent and he could become a serious liability on the defensive end. Plus I see little potential for improvement, I just think he is who he is. He already has the full complement of offensive skills so he isn't going to develop much in that part of his game, and his defense sure as hell won't improve, nor will he become a better athlete. He might be the best player in draft right now, but I seriously doubt he will be two years from now.
Embiid has a real chance to become a superstar at the NBA level, and to be honest even his worst case scenario (elite defender and rebounder who can score inside-out) would be of great use for the Celtics. But the back issues worry me...a lot. I've seen too many elite rookies come in to the league hailed to be the next big thing, only to have their careers destroyed by injuries - Oden, Brandon Roy, Penny, Bynum, McGrady, Grant Hill, etc. In recent years the great big-man prospects in particular seem to have suffered a lot from this. If you're drafting 5th or lower then sure, I can justify taking a gamble on a high upside player with health issues, becasuse the player is so much better than the other available players that it's worth the risk. If I'm chosing top 4 though in a draft with this much potential, the risk is just too high IMO.
Wiggins is healthy, but more importantly to me he's just such a complete player. He probably has the highest upside of anybody in the draft, yet even right now he is already:
* A good shooter
* A good ball handler
* A good passer
* A good rebounder
* An elite defender
* An elite athlete
* Capable of playing multiple positions
A lot of people are saying Wiggins reminds them of Jeff Green because of his lack of killer instinct, but what people realise is that it's Green's skill set (not his mentality) that tends to hold him back from being a superstar. He has a poor handle, he's not a great passer, he's not a great rebounder, he struggles driving to the left, etc. Wiggins has none of those weaknesses in his game at all, and if he develops his game he will become a superstar, even if he does lack that killer instinct.
You need to think about guys like Duncan, Lebron, Jason Kidd, Kevin Garnett, etc. You could argue that all of those guys lacked 'killer instinct'. Duncan is a quiet and laid back as they come, Lebron was soft up until about two seasons ago, Kidd was always a quiet achiever, Kevin Garnett was always criticised for being too unselfish and not always being the guy who wants to take the last shot. At the end of the day it doesn't matter - every one of those guys is a future hall of famer.
Ironically my second choice wouldn't be Parker or Embiid either - my #2 choice would be Exum. I think his ceiling is right up there with Embiid and Wiggins, only he doesn't present the risks (health concerns, poor basketball IQ) that Embiid does. He'll probably fly under the radar because he didn't play College in the states, but don't be surprised if 2 years from now, he is the best player from this draft. Plus the benefit of taking Exum is two-fold. If we keep him we can start him at PG alongside Bradley, and then trade Rondo for (a) a second top-10 lottery pick, or (b) fringe All-Star (Greg Monroe, Josh Smith, etc). Just imagine the type of defense and speed you could get from a team like:
PG - Dante Exum
SG - Avery Bradley
SF - Jeff Green
PF - Josh Smith
C - Willie Cauley-Stein
Could well be the best defensive lineup in the entire league...and then next season you can use the extra $15M cap space (Green and Bass come off the books) to sign a relatively young max-contract player.
My #3 choice would then be Embiid because lets be honest - even with his IQ, attitude and health issues, most teams would still trade half their roster to get Dwight Howard on their roster. Embiid has the potential to be the next Dwight Howard at worst, and at best he could be the best center since the golden Robinson/Ewing/Hakeem/Shaq days. A guy with tht type of upside (health risk or not) is either a building block of the future, or one hell of a trade chip.
My #4 is a tough one. I might actually shock the world, skip on Parker, and take Marcus Smart. I think this kid is going to be better than people anticipate because:
* He is a two-way player (who can score and defend)
* He has the intangibles (leadership, work ethic, fearlessness) to be a franchise player
* He can play multiple positions and is very skilled at his position
I can very easilly see Smart becoming Dwyane Wade 2.0, and while he still needs to improve his jumper you have to remember...Wade has never really developed an above average jumper, but was still a top 2 SG in the league for up until the big three era began.
Then my #5 choice would probably be Parker, #6 Vonleh, #7 Aaron Gordon, #8 Randle.