Cuomo is more likely. Schumer has the potential to face a strong challegne from Durbin, while Cuomo's election is assured.
This. In fact, it's actually possible that Reid remains majority leader, assuming he's reelected. And even if he steps down or loses, Majority Leader Schumer isn't a sure thing because of Dick Durbin--in fact, if Reid steps down or loses, I'd actually give Durbin a slight advantage, given his current status as majority whip, as well as being from Illinois.
On the other hand, Cuomo's almost certain to become governor.