Keeper League Trade-Stephen Strasburg or Jason Heyward??

I had the day off on Thursday, and while the kids were watching cartoons on Nick Jr., I decided to read through Matthew Berry's ESPN fantasy chat and thought this question would spark some conversation on the site:

Andy (Omaha):

would you trade Strasburg for Heyward in a keeper league?

Berry:

No

That is an interesting question as you have the best pitching prospect called up in 2010-Stephen Strasburg vs the best hitting prospect called up in 2010-Jason Heyward. They were ranked either 1-2 by most prospect experts coming into the 2010 season. Heyward has been, to this point in the season, the top candidate to win NL rookie of the year, but I think by the end of the year Strasburg will have something to say about that. That is, if Strasburg continues to dominate lineups like has in his first 4 major league starts.

Who would you rather have in a keeper league?