SRL put in a great effort to make himself smarter for the purposes of marketability. Apparently, he used to read the dictionary in an effort to become more articulate, and the way he managed his career was very cool and calculated (which is part of why he's still filthy rich even now.) DLH as a businessman has impressed in recent years, though some of his decisions in the ring (brawling with Mosley in the first fight, putting the Pacquiao fight together, not hiring Floyd Sr. for the Mayweather fight, moving up to middleweight, etc) left something to be desired. The Klitschkos, obviously. Juan Diaz and Barrera are both lawyers out of the ring. JMM is trained accountant. Harry Wills was apparently a successful real estate investor out of the ring. Gene Tunney was also a very cerebral fellow by most accountants.
Inside the ring. Benny Leonard Floyd Mayweather Jr. Ray Leonard Willie Pep Outside the ring Fidel LaBarba (Stanford) The Brothers Klitchko. (Both are Doctors as in they both earned Doctrate degrees, it's not just a nickname) Marco Antonino Barrera (Studied Law) Juan Manuel Marquez
I would have said Roy Jones, but seeing that he is so delusional these last years I'm not sure anymore