Good post Juan, but I do certainly think Rafa with some support, is THE best for this position.
We know what he can do, everything has already been set up through his blue print, the academy would by perfectly in sync with the first team, lots of cash is not required in comparison to some managers, you know he wont walk out if another job comes up, he is also analytical and methodical in his approach. I reckon there is a lof FSG would admire in Rafa the candidate. In addition, he is proven in the premier league, and in the club, his signings have been very astute (generally speaking).