Wouldn't count out Ortiz. We know how the voters will react to it being his last season and stuff, I'm sure he'll get a good chunk of votes.
Though I think it's between Donaldson, and Altuve. If the Astros don't make the postseason, that will be taken into consideration. Trout should be in the conversation as well, though only with 21 HR's and playing on a losing team, the voters won't give him much acknowledgement.