So I've thought about this match for some time now, and I'm still on the fence. So I'll go though this one step at a time. However I want to make something clear about Gotch. He was a pro wrestler. When he made a name for himself working in the Yukon and Alaska, he came back to the States with over a million dollars to his name [era equivalent] in about a year. That's about $50,000. The average yearly salary at the turn of the century was $500. George Hackenschmidt, when he was at his absolute peak as the most well known sports star in the world was banking about $1,750 a week. And Gotch amassed this money before feuding with Jenkins for the National title. There's no feasible way in fuck that Gotch could have made this money in straight shoots alone. That's how we know for certain that he largely participated as a pro wrestler during that time period.
Drawing power - I've debated this with myself and I'm going to go with Gotch. Most of us over the years have come to realize how massively fucking popular El Santo became in Japan. And he was. But Gotch was massively popular all over the world. Americans knew and loved him. Canadians knew and loved him. Europeans knew and loved him. Indians knew and loved him. And the Japanese knew and loved him. I can't really say for certain how popular Gotch was in Mexico, but considering that wrestling there was popular before Santo became a mega star, there were international Mexican wrestlers who became known in the States before Santo, and that relative contemporaries like Strangler Lewis and Jim Londos were popular in Mexico later on leads me to believe that Gotch would have been popular there too.
Santo was primarily only known in Mexico until decades later when he began to gain followings outside of his home country, primarily due to his crossover appeal. But that applies to Gotch as well. One of the reasons he became widely known internationally was through Vaudeville. He would tour everywhere with his plays and then work matches. He defeated a known jujitsu master on the floor of the Oval Office in a shoot contest for the amusement of Teddy Roosevelt, so the Japan knew whom he was and they respected his abilities.
I will say that Santo was more marketable. Clear. He had far more mediums: comic books, television, movies, radio.... not just theater. But I will counter that with Gotch appealing to a much broader and larger audience than Santo did in a much shorter time frame.
And as far as sheer recognizably that has to be Gotch. This was a man that would go to a Chicago Cubs game in the 1910's - when they were already well known World Series champions - and the players would all line up afterwards to get his autograph. Santo has statues raised in his honor, but so does Frank Gotch. Santo's funeral drew thousands, but so did Frank Gotch's. Santo is still widely remembered 30 years after his death, but Frank Gotch is still widely remembered a 100 after his.
This has to be a point for Gotch. I cannot see it any other way.
Longevity - This is a clear point for Santo. His career lasted several decades longer than Gotch's [due to Gotch's untimely death] but Santo remained a top star the whole time.
Consistency - Gotch lost approx. 6 professional matches. Most of those came from Tom Jenkins. But Gotch finished the feud with a record of 8 wins to 5. Santo had a losing record against his top rival Blue Demon. Another point for Gotch.
Charisma - Both of these knew how to talk, act, and deliver. There's nothing one man could have done better than the other man in this category that could be documented. However I'm going to give this point to Santo due to his marketability advantage. He was more popular across more mediums than Gotch. Point Santo.
Accolades - Santo was never a world champion. But he was a decorated light heavyweight champion. Though he was undefeated in Lucha de Apuesta matches, which at times were considered more important than world titles. Gotch on the other hand was a 3 time national champion and held the world title for 5 years. Where he defeated all comers. Including Stan Zbyzsko, whom had amassed a 900+ match winning streak before being taken down by Gotch. I think Gotch should get this point due to his longevity as a world champion.
Overall legacy - Santo was the most popular wrestling star in the history of Mexico and popularized Lucha Libre. Frank Gotch on the other hand was quite possibly the most popular pro wrestler ever and accomplished 100 years ago what the WWE is trying to do today: and that's make pro wrestling a household thing all over the world. Frank Gotch made wrestling big time, and not just in one country. Even Mexico's biggest star can't say he did that. It's something Rikidozan will face when he goes up against Lou Thesz this round. Gotch was still being featured heavily in advertisements, sport publications, magazines, books, and documentaries decades after his death. For most people, pro wrestling starts with Frank Gotch.
In ring skill - Most subjective category. Even though Santo was a technician he wasn't on the level of Frank Gotch. Most of his countrymen didn't see him on the level of Gory Guerrero either. Frank Gotch wrestled outside of his weight class on a consistent basis and defeated numerous strongmen. Like Stan Zbyszko and Hack. And he defeated numerous opponents that were smaller and faster. Like Jenkins and Farmer Burns. Food for thought. Santo was relatively the same size as Gotch, and struggled against opponents like Blue Demon. I'm leaning Gotch.
So in categories like consistency and drawing power and popularity, Gotch is the clear better of the two. And he was the undisputed world champion, and was toted as the best wrestler in the world for 5 years. Santo never received that distinction. Of being the best wrestler in the world. Even in his prime.
All things considered I am going to give the win to Gotch.