He can see the way all the other players who went to City have failed. He also knows he'll possibly be hated (or close to it) by the supporters of the club he supposedly is a lifelong fan of if he goes to City. Also think of the problems that would be caused at Arsenal if he went to City, with the players already there and all. To his supposedly favourite club...
The obvious reason therefore that he would go to City over Juve is the money. Plus, add to that the fact that Juve don't really have any top strikers, and City have Aguero (who I think will have a better season than RVP no matter where he is next season), Tevez and Balotelli. He'd basically be handed a winners medal by being one of the minor members of the squad IF they win, whereas at Juve he would earn the medal by contributing a significant amount to the team.
Plus, add to that the fact that his father has said he wouldn't want RVP at City. It isn't what makes his decision, what his father says, but still, all these little things add up.
The Arsenal column: Why Robin van Persie will still be an Arsenal hero if he moves abroad but hated as a traitor if he goes to Manchester United or City - John Cross - Mirror Online
Interesting article on the matter.
Oh and if he wanted to play for a successful team likely to win silverware, with other great attackers around him like he would at Man City, he would be off to Barca or Madrid surely.