Garry Russel Jr is pretty damn good. I like the guy and he is pretty talented.
Andre Ward is charming and all he really needs to make it big is a big PR push because in terms of legibility, he has it.

Asides those two I don't see anyone else and the reason really is America's piss poor amateur system. Compared to college football/baseball/basketball amateur boxing in US is shit. So when you hear a guy is a golden glove champion it doesn't mean as much as it used to way back in the day. So when an Eastern European boxer takes him to school no one should be shocked. Same thing can of course be said of Cuban boxers and their very deep amateur talent pool.

Long story short if America really wants to have big named boxers rather than being the best platform for boxing it needs to invest into its amateur program.