Not saying he was the best, but I really liked Espana. Ge pretty much ended Meldrick Taylor's career as a top fighter and looked destined for a great career until he met Ike Quartey. Ike walked him down and Espana moved on from boxing.
Another vote for Betulio Gonzalez. A top 2 Flyweight of all time could barely separate himself from Betilio over 3 x contests.
Luis Estaba. Guy in his late 30s running around with a recently created title against the chintziest of contenders, back in the day when that was actually a novelty. Called "Lumumba" because of his resemblance to a deceased Congolese politician. After he lost to a guy who was 4'10" the Venezuelan commission stepped in and said, "Sorry, you're too old. You're not allowed to fight anymore." Everything about him is mysterious and fascinating.
Esparragoza. A staple on Monday night's 'Fight Night' in the UK (late 80s, early 90s) and reminded me a lot of Arguello. His time at the top was too brief but his title-winning effort vs Steve Cruz is one of my fave fights of that era.