Both would be great options, but whne it comes to giving up the few prospects left that are tradeable, I think that the Sox should be careful and put them in the area that is most needed. In my opinion Willie can get on base and is a leadoff hitter, so if the Sox are to acquire anything, it would be a semi replacement for Maggs (maybe Danny Bautista), a quality reliever, or a quality starter.
Just my 2 cents. However, if they can be had for cheap, thats another story, but I don't think its too likely.