In Canelo Alvarez and Sam Langford, they were, at one point, the best fighter in the world from 160 lbs to 175 lbs. How would you imagine a fight between Alvarez and Langford playing out?
No fighter from that time frame could compete with any modern fighter. Boxing has evolved since then. It has dramatically evolved. Sam Langford is so crude by modern standards that even the worst amateurs are more skilled. Canelo would destroy Langford.
I'm guessing that we're talking about Canelo's evolved form, Clenelo? The one that doesn't need a light to take a leak in the middle of the night because of the radiocactive glow from all the peds he took? The guy that's shredded to the nth possible degree? I might go for that guy.