Julliard (NY Phil Basses, Eugene Levinson, Orin O'Brien, etc.)
Peabody Conservatory: Ira Gold, Paul Johnson, Jeffery Weisner
Cleveland Institute of Music: Scott Dixon, Max Dimoff
Northwestern: Andrew Raciti
The answer depends on what kind of student you are. If you are very hard working and are willing to practice till your fingers fall off, there are teachers who will guide you to virtuosity. If you are lazy, no kind of teacher expertise will help you with that.
I've studied with Anthony Morris, who teaches in Brooklyn College. Although the Conservatory is not known for mass producing bass virtuosos, Prof. Morris is a working pro who is able to take a beginner from Simandl book 1 to Difficult Bottesini Waltzes (and get you playing them like a champ) and so on. Good luck.