If you take away the fact that this is Abreu's first year outside of Cuba, in a vacuum I would take a 28 year old 3B producing like Donaldson over a 27 year old 1B producing like Abreu. The one thing that gives me pause is the belief that because Abreu came here from Cuba, he may have more room between his current production and his peak than the typical 27-28 year old. Also, the Sox have a good 3B in Gillaspie and another potentially good one in Davidson, with no real 1B prospect behind Abreu.
But yeah, if I'm starting a team from scratch and have to choose Donaldson or Abreu for the same money, it's a close decision.