One of the fighters that always comes to mind for me is Randy Smith. A journeyman of sorts who fought throughout the 80's and 90's. Record of 29-33. Looking at the list of guys he fought without folding up even once is impressive. Your pick?
Lovemore Ndou. 49-13 never Koed and look at the names he fought. All decisions losses - Cotto, Canelo, Kermit Cintron, Kell Brook, Junior Witter, Malignaggi, Sharmba Mitchell. He was also Kostya Tszyu's sparring partner for a very long time.
Although he was KO'd, I still think he had a great chin. Jesse Ferguson, he beat Mercer and Buster Douglas.
Garry mason.well know in Britain at the time but not now .Rock solid chops even Lewis couldn't move him.RIPchamp
Willam Page went the distance in a 6 round fight with Julian Jackson. JJ said in the Ring Mag best i ever faced Q & A. " I remember fighting this white guy and i hit him with the sink and he wouldn't go down ." Though William Page rec showed him being stopped 8 x he seemed to leave quite a impression on JJ .
Maybe a guy you asked about a few years back? https://www.boxingforum24.com/threads/danny-blake.55047/
I've only seen one fight of Zeijko Mavrovic, but it's enough for me to want to mention him. This content is protected My god.