I voted for Connor. I think all three are going to be very good, but I think in Jackson's case the organization has screwed things up with him. From when they called him to the big club last year so he could sit, to the seemingly every other day-day off this year, and then being put in the cleanup spot where he really has no business being.
Plus, I think we're all forgetting tha 1st Base isn't a position he's grown up playing, so his defense will naturally be behind that of Drew and Quentin.