Sanchez. Better at picking the punches, going in and coming out, is my answer. It's a crude answer, and the difference isn't that huge, but I think it would really start to tell the longer the fight does go.
For me Sanchez's footwork gave him dominance in both his offense and defense. He was even elite both defensively and offensively inside. He combined that with workrate and speed, simply dominating oponents through every facet. I'd put Sanchez as no1 FW of all time, it's pity for his family first most that he passed early but you really wonder what could of been. Already dominated so many great fighters but the sky was his oyster. Ofcourse he could of lost motivation like many fighters so we never can know. He was taken from us in his absolute prime. Marcel's ringsmarts and toughness let's him see out the final bell I think, but the stoppage could happen.
I could have sworn this originally said Marcel vs. Saldivar. For this, I’d go with Sanchez by close decision.
Took a little time to review footage of both of em and yeah, I'll take Sanchez (as expected). Marcel would still make it a fight, no stoppage, won't be too one sided, but Sanchez was on a different level. I'm not too knowledgeable about either, though.
Sanchez for me. Unlike some other technicians Sanchez had the legitimate toughness and spitefulness to deal with Marcel. People talk about Marcel's technique and agility but a lot of his success came from being quite physical and implementing dirty tactics, such as forearming, elbowing, lots of shoving and rushing in with his head after the inverted 1-2. He did it a lot against Gomez and Shibata, which really threw them off despite their skills. Sanchez however had the strength, toughness and mental focus to deal with and land some brutal counters. You see how he deals with this type of aggressive 'push' tactics against Nelson. I think Marcel matches up much better against less physical technicians like a Famechon, or even a Pep, than Sanchez.
My main problem with Ernesto Marcel is his utter refusal to speak on camera. It could count against him with the judges here.