I think I'd take Huff. His horrible start last year indicates that he might have a significant improvement if he manages to avoid a slump like that this year (similar to Tejada from '03 to '04). And even though people are saying that A-Ram has a better park, better lineup, etc., what's really important in projecting how a player will do this year is analyzing what's changed in comparison to last year. For A-Ram, I'd say the lineup's gotten slightly worse, although he'll probably be hitting in a better spot, so there's probably not much overall change. For Huff, the lineup around him is consantly improving.
But as others have said, position eligibility is the key. If you haven't drafted a 1B or 3B yet, you can just take Huff, and it dramatically increases your options as the draft progresses, since you know you can take either a 1B or 3B. Of course, if you've already drafted a top 1B like Pujols, Teixeira, Thome, Ortiz, or Delgado, then it's hard to say which one you should take...I happen to like Huff, but going purely by past stats, A-Ram may be the smarter pick.