Both would be solid options. While I think Thomas will have a bounceback year, I don't see him hitting over .285. 30 hr's and 100 rbi seem attainable though. The one drawback i see with Thomas is he has no position flexibilty, he only qualifies as Util/DH. Of course, those numbers are good from a util/dh position.
Huff is a legit .300 hitter and I expect him to put up better numbers than last year. .310, 25 hrs, 85-90 rbis. he could also play 1B for you if you starter gets injuered. Just something to think about.
I guess if I had to pick between the 2, I'd pick Thomas over Huff, but not by much. For what it's worth, Thomas went in the 12th round of my draft, Huff 14. So you could probably get both if you wanted to.