RyNye, I think that him being the surefire number 1 (and I think the claim that he's the first surefire number 1 pick in years is inaccurate media hyperbole - Blake Griffin in 2009 and John Wall in 2010 were the undisputed top picks, and while they ended up being incorrect, Oden in 2007 and Bogut in 2005 were concensus choices) has more to do with the fact that this is a deep, but not at all top-heavy, draft. There are a lot of NBA players to be had, but I don't think anybody has that good a chance to be a superstar.
Davis is closest because he's an extremely athletic big man with a lot of length, a nice (not great, but nice especially for a big man) outside shot that due to his height, arm length and leaping ability, he will be able to get off over anybody, and most importantly he's ready to step in and play NBA defense right away with the potential to be a game changer on that end. Great shotblocker, good communicator, quick feet, and athletic and long enough (7'4" wingspan) to defend multiple positions. He also is comfortable with the ball in his hands but doesn't need it. He also is by all accounts a great kid who always plays and works hard. Just a lot of skills, natural talent, athleticism and of course you can't teach size (or work ethic).
Over the last few years, teams have realized more and more exactly how important it is that your star players play defense and that's helping Davis too. He'll never be one of the 10 or probably even 20 best offensive players in the league, but in a short time he could be one of the most impactful defensive players while giving you solid efficient offense.
Frankly, I think guys like Kidd-Gilchrist (if he develops his outside shot, already has the ability to attack the rim, plays hard, and is a good perimeter defender), Andre Drummond (if he had the same level of dedication as Davis, at 6'11", 275 with a 7'5" reach, he'd be number 1), and Jeremy Lamb (if he got a bit stronger and asserted himself more) have higher ceilings than Davis. But Davis has far less of a chance than any of those guys to fail at the pro level. With his size, skill, athleticism and already proven work ethic, I don't think there's any way Davis is a bust, and any of those other guys could be.
One additional note: a main reason I think Kidd-Gilchrist has a higher ceiling is that when I watch Kentucky - and this could be more a function of which of their games I have seen - it's clear that Davis is the best player right now, but Kidd-Gilchrist can take over on the offensive end much more, and when he gets going, it seems like they hit another level. But Davis is at the top because he's still doing his thing at those times, and keeps Kentucky in every game when MKG or Jones isn't taking over.