I'm kind of high on Hill because I think he's heavily underrated. That being said, I'm not sure he'll be hitting 40HR like his numbers from the first half suggest. If he does... wow. But that's a big gamble. I'm thinking you're going to see steady RBI, R, and AVG out of him, but not all that power the rest of the way.
We know Hanley is more or less proven quality. Upton is in his first full year, and in on a pretty anemic team at times.
To me, this trade goes like this:
Team A gets two proven talents, one still definitely on fire (Hanley), the other struggling a bit lately (Santana).
Team B gets two question marks and one of the best closers in history.
Team A wins here I think, based on track record and proven ability. That being said... if Hill and Upton keep it up, then hell B could crash A in this trade. I'd stick with Hanley/Johan if it were me though I think.