Dick, obviously.  He's practically the son of the Dark Knight.  Yeah, Damian is Bruce's blood son and has promise, but he still has much to learn.  Maybe further into his career we could see, but not yet.

Grayson on the other hand, has been part of the families (Waynes and Bat) for the longest time.  Not to mention Jason going bad, and nearly framing the cowl.  Plus, I still personally see Tim on the uh..."Nightwing level", I guess you could say.  And while I like Batman Beyond, I still view it as only one of the many "possible futures".

So bottom line, Dick Grayson, hands down, as the new Batman.