For a more modern consideration (Linares is one of my favorites so I enjoyed this analysis) https://www.ringtv.com/517756-best-trained-ismael-salas/
A couple of other guy's that deserve mention for what they accomplished in the amauter game are Kenny Adam's and Uli Wegner. Adam's trained all of the top US guys in the 80's and 90's (Sweet Pea, Holyfield, Roy, Taylor etc.) While Wegner had Ottke, Maske, Abraham and Beyer.
he should have been kicked out of boxing for the way he blatantly lied about Antonio Margarito and the Plaster Blocks he claimed he saw
All he did was LIE about PLASTER BLOCKS with Antonio. All that was in Margarito's wraps was a used soft gauze pad which Javier Capetillo admitted he put in by accident as it was in his bag. This pad was deemed HARMLESS by the lab that eventually tested it. There was "Nothing hard" in or about Margarito's wraps Richardson is known for pulling **** like that to try to get in the opponents heads. I notice you dont mention Mosely was almost certainly juiced to the gills AGAIN!! in that fight
Charles Atkinson was from the UK, but made a name for himself teaching Thai boxers, Sot Chitalada probably being his most famous.
As mentioned Angelo Dundee and Lou Duva were superb 'cornermen' but far from the best 'trainers'. Benton rightfully gets a mention. Steward was brilliant at offence, but if I had to pick one, it is cliche, but Eddie Futch is King.
Some excellent mentions so far. Joey Fariello always gets left off these discussion for some reason, so I'll mention him.
A few more i would like to mention are Al Silvani who has a really decent resume behind him, Slim Jim Robinson and Chickie Ferrara. Slim had a lot of input into Eddie Mustafa Muhammad, Mike Rossman and Tim Witherspoon. Chickie shared the corner with Slim and came up with Mustafa's great countering moves against Johnson and also had quite a bit to do with Ali.