HWs - Holmes, Lewis, Wlad, and Ibeabuchi come to mind. Lighter weights - Quartey, Hearns, ODLH, Barrera, Morales, and Forrest come to mind. I am sure there are others that I can't remember at the moment, but these are the ones I came up with for now. Out of all of them, I would say Quartey's jab was probably the best, IMO.
I was considering all these different boxers who are known for their jabs For me the light came on when you listed Carlos Monzon. When you talk about controlling a bout with a jab. I don't know if his is specifically the best but I don't know of anyone who used theirs better than he did. He was effective. This content is protected
A guy like Willie Pep hasn't been mentioned, he's deep in the running. Lopez is in the mix as well. There's been dozens of truly great jabs, it's the cornerstone of boxing.