Im going for Iran Barkley who not only fought (and beat) some great fighters but did so from middleweight to heavyweight. 43 wins but 19 losses!
Randy Sandy beat Emile Griffith and Dick Tiger, had a close fight with Joey Giardello and ended with a record of 24-24-2.
Emile Griffith. Most Classic posters will have him in their all-time top 30s, and I think his win-to-loss record is something like 85-24. Griffith is far, far more highly rated than guys like Glen Johnson. I personally rank Griffith much higher than guys with zeroes like Marciano, Mayweather, Lopez and Calzaghe.
Castillo's record looks like crap but most of his losses were against some good fighters. Freddy Pendleton was a top fighter with a horrible record 47-26-5 and he was one of the best lightweights at his time. Drew Bramble, Ko'd Bramble, Ko'd Uncle Roger, went 12 with Whitaker, Decisioned Paez, and Beat Spann, Lost a tough fight with Rafael Ruelas, TKO'd Tony Lopez...he was about 21-15-3 when his career turned around