All 3 have mad skills...this I'm fairly certain about. That being said, if I had to choose a player I'd choose Dzeko seeing as you're not going to find anyone with his eye for goal in Italy, Spain (barring David Villa) or any other EU country. Juventus needs this type of player STAT! They blew 22 million euros on Amauri after a mediocre season for fuck's sake. Dzeko is consistently pumping in goals. Dare I say à la Trezeguet?
Pastore would be my second choice; he seems to have quite the magic touch and, equally as important, has his head screwed on right. My only hesitation is the fact that he's playing for Palermo and I'm sure they'll rob Juventus as much as they can. Juve can't afford that; fullbacks are also a requirement.
Finally, my last choice (and I mean LAST choice) is Neymar. Yes, he's got skills. Yes, he seems like he'll be a big star (Robinho, say what?). However, he's a headcase and I'm almost 100% sure he'll cause problems within the squad. At Juve you've got to leave your ego outside the gates. If you're gonna shop Santos, get Ganso. Echoes of Zidane and also sans ego, my word.