All good choices. Those Latin fighters were masters at countering off the ropes. Shout out to Galindez on that note. It was fun to watch IMV. Wilfredo Benitez as well.
Napoles is the man. Tho slightly alternative to your common CP i think Archie Moore is fantastic in this area. Of more modern fighters McCallum of course. He could be quite clinical at times.
Juan Manuel Marquez was the best counter puncher of the last generation. All time? Benny Leonard deserves a spot on the list
Napoles takes the cake for me Holyfield was an underrated counter puncher, far from the best ever but a very good one.
Napoles, Duran, EMM are all good shouts, Moore etc. Medel was a beast at bantam, he set Mooresque bear traps and walked people into them. Dick Tiger. He has a rightful reputation as being unbeatable in a tear up and even with monstrous strength, resilience and work rate you don't acquire that kind of reputation without being a very sophisticated counter puncher. Harold Johnson. Perfect form and timing to exploit created openings straight from the textbook, not something any man should be able to do to Ezzard Charles. Most of the greatly talented defensive freaks: Pea (RIP), Pep, Locche, Zapata, Lora, Benitez, Kalambay, Canto Tec were all top notch counter punchers. Kalambays counter-uppercut from the outside is one of the best damned punches I've ever seen from a middleweight. Bob Foster was a fine sneaky puncher. You generally have that image of him stalking with that hunched menace and getting off first on retreating opponents with upward jabs but there were few better at inserting unanticipated slingshot effect hooks during aggressive exchanges to such devastating effect (even if could look skittish under heavy fire himself).
Holyfield is a good one at heavyweight, up there with Louis at baiting the dividing space. The fact that didn't give a **** about getting hit and didn't have good defensive reflexes or one punch power made it even better because bigger guys would just go after him carelessly and get pinballed by counter combinations.