I think Juan Manuel Marquez would hes super smart and knows what to tell a guy to do to win it. Just Look at the Golpe A Golpe videos.
Given the history of the best trainers throughout the years, probably some amateur fighter or journeyman professional we don't know. Most great fighters do not have success as pro trainers.
JMM, Hopkins is a popular pick too. I'd venture Malignaggi, a highly skilled boxer who's articulate enough to get his point across. Though I'd much rather hear him commentate.
Good call on Paulie. I also like JMM. I think a fighter who doesn't have one punch KO power and has to use the subtilties of the game to win will have a better understanding of boxing as a whole and therefore more knowledge to pass on.
Laila McCarter. A nifty ring general with as educated a jab as there is. Watched her train a fighter or two at Johnny Taco's Vegas gym. She breaks every move down clearly and is very patient. Some smart manager would be wise to give her a shot.
I like how Hopkins uses old school fundamentals. His boxing know how is why he is a champion at this stage of his career.
I think it has more to do with being humble. Fighters that never made it big will want to show fighters how to succeed beyond them, and that for them will make them feel like success. Very decorated fighters may feel like they know so much and that their way is the only way. They may even forget to explain the details and the theory behind a technique. Sometimes they think if somebody doesn't get what they are saying it because they are a bad student rather than their teaching. From an outside perspective I think JMM would maybe be humble enough to make a great trainer. I'm not sure about anyone else, but I think Hopkins wouldn't be patient enough. He could probably work with fighters who already have somewhat of a pedigree, like when DLH fought Shaq :yep
I guess either some very technical boxers or journeymen or boxer who faced really really many boxers with different styles
Finito Lopez, Tommy Hearns, Kostya Tzsyu. Those 3 very calm, very nice outside the ring, but inside true terrors. Need to be very patient as a trainer not for everyone.