Best/favourite, whatever. From what you've read about these mythical legends, who's your No.1 choice?
Greb is the obvious answer, so he isn't my answer. I'll go for John Henry Lewis. JHL is supposed to be one of the, greatest light-heavyweights ever. He is undefeated at the weight, beat some brilliant fighters like Maxie Rosenbloom, Bob Olin, Jock McAvoy, Tiger Jack Fox etc. He also was said to have it all; speed, defence, smarts, skills and from his record you can see chin, power and class. He dropped Maxie Rosenbloom twice with body punching, and he was only ever KOed once in what I actually think was a dive. Given that he fought for years, blind, he clearly has heart too. I'm pretty sure the return fight between him and Braddock (a green Lewis then) was filmed, but it's not available. The fight with Louis is also available, but it's about a minute long and it's the grainiest footage I've seen from Louis.
Greb is an easy choice. Other than that, Maxie Rosenbloom is among the best. Tommy Ryan was quite special and so was the original Jack Dempsey.
I'm going to go with Tiger Flowers. Apparently you had to knock him out to beat him and whilst his chin was there to be cracked, I'd love to see his defensive swarming style in action. Ideally I'd like to see him in his title winning fight, whoever that was against.
I feel like Greb is a pretty obvious choice. Tommy Ryan is up there, I wish I could see him in action.