Dynasty League Dilemma's: Bryce Harper or Mike Trout?

Over at Halos Heaven, The Limey, whoever that is, introduced the idea of a Mike Trout and Bryce Harper swap. While that deal makes sense from a baseball stand point, and it certainly does if you read his argument, I immediately started thinking about who I'd rather have in dynasty. In the early parts of a currently on going dynasty draft, I passed on Mike Stanton with a second first-round pick in order to grab Evan Longoria and follow that up with Bryce Harper, at least that was my intention. My plan almost worked, as Harper went three selections before mine. I then turned to what I believe to be the next best thing by drafting Mike Trout. He doesn't have Harper's power but he does have the build and projectable strength to cast visions of 20+ home runs. What he does have for a fact is superior speed making him a potential five category threat in roto. Harper could be seen as that as well, though I believe Trout will consistently hit for a higher average. But it begs the question, if it came down to Harper and Trout, who would you choose and why?