Hollinger's player rater thing is out but its for ESPN Insider subscribers.
A couple of things, on Leonard:
If I had to peg two other perimeter players that I would guarantee to at least become solid rotation players, it would be Kemba Walker and Kawhi Leonard. While this year's draft doesn't project to have a lot of star talent at the perimeter positions, Walker and Leonard are the two who rate above 12 -- which, historically, has been a guarantee of at least being decent.
On JV:
My Euroleague translations say two players in this year's draft, Jonas Valanciunas and Nikola Mirotic, would be rotation players immediately if they came to the States. Valanciunas rated higher, with a translated PER of 14.70 (albeit in limited minutes) compare to 13.66 for Mirotic. Of perhaps more importance is that Mirotic is contractually bound to stay in Europe for a few more years. He'd be a top-10 pick on my board if it weren't for that; as it is, I've dropped him behind all the players I consider relatively safe bets.
Vesely:
The other top European prospect, Czech forward Jan Vesely, doesn't grade out nearly as well. His first-year PER translates to 10.72; while one supposes he would improve further from that point given his youth and athleticism, it still makes him somewhere south of a sure thing. I've listed him as a top-20 pick based on potential and the general weakness of this draft, but taking him in the top five or 10 would be a mistake.
Kanter:
Kanter is sort of the anti-Biyombo; He's not much of an athlete and will be suspect at the defensive end, but has such a high skill level offensively that he's going to score relatively easily. A good comparable might be fellow Turk Mehmet Okur, except Kanter is probably more skilled with the ball.
There's a lot more, I just posted stuff about guys we're looking at. I didn't include Bismack because I'm not sure if he's even on our radar.
So just to recap: Kanter seems like a safe bet, so would JV, stay away from Vesely, and Donte M (the euro guy) are worthwhile choices later in the first round, but have questionable strength and athleticism.