Ike Ibeabucci has to be the biggest really good but.. fighter I can think of. He was the total package, speed, power, skills, size and conditioning. He just literally lost his mind.
Edwin Valero is another. Yeah he won a belt, but he could have been so much more. People who I value their opinions greatly swear that the version that was killing guys in the So Cal gyms in the early to mid 2000's was much better than the version that beat Demarco. Valero's drinking and drugs had already taken a toll on him by the time he started get shown on US television.
I actually think David Price had all the physical too. Weak mentally though. No confidence in himself
It wasn't that Kostya didn't show heart in the Phillip's fight. It because he NEVER tried to avenge that loss. 