Gene Tunney. My pick as well. This guy was fighting with a style very similar to Ali's before Ali came around. He was very successful with it and very hard to beat. Tunney a true ATG that would give any HW of any era a very hard fight.
Good point Swarmer, many people aren't open like you & I to the older times. I'm glad for what footage is obtainable and love to see older fight and usually prefer them over nowadays fights especially old-time heavyweight or middleweight fights. Yep a true thinker in the ring. It's a shame there isn't much footage of him because I'm a big fan and would love to see his battles with Greb.
Jose Luis Castillo only ever gets mentioned as a stick to beat Mayweather with over the close debatable fight but was a very good fighter in his own right with a very good run at 135
If we're talking about current active fighters - I would have to say Andre Ward is the most underappreciated fighter. Ward is a future #p4p candidate and it is only a matter of time until everyone is talking about him.
Jose Luis Castillo. Best lightweight of the decade. Beat Johnston, Diaz, Lascano, Paez, Corrales and Casamayor. Probably wont get Hof.
My choice for all time underappreciated fighter would be Emmanuel Augustus aka Emmanuel Burton aka the Drunken Master. He had the unorthodox ability of a Roy Jones, the heart of Arturo Gatti and the propensity to brawl like Ricky Hatton. He was the B-player on a lot of great fights including the fight of the year 2001 with Mickey Ward. Augustus had all the talent, speed and technique he needed to defeat anyone - but he always ran hot and cold. Augustus' style and use of broken rhythm made him a stylistic nightmare in the ring because no one else fought like that. Floyd Mayweather often goes on record by stating that Augustus was his toughest opponent.