As a piece of evidence - McGregor has 8.47 million twitter followers, Canelo has 2.4 and Pacquiao has 1.6, Fury has 1.7, Wilder has 700k, Garcia has 500k, Loma has not even 200k, and GGG has 600k
So just based on twitter here, McGregor has more fame than Canelo, Pacquiao, Fury, Wilder, GGG, and Garcia combined. (8.47 to ~7.9 million)
So if the argument is TODAY, which sport has the more popular stars? It's MMA. Easily. I'd count Khabib in there as a pretty big international star, we're not counting Ronda. We really cannot count Mayweather. I mean fuck the UFC was just on ABC and has inked deals with Fox and ESPN in the past, so yeah it's surpassed boxing imo in popularity.
edit: Went back and read every comment and realized this thread is retarded.
People equating anyone to Muhammad Ali is just so autistic it kills my brain cells. Ali was a historical figure, he was drafted into the Vietnam War and didn't go, he was a black/muslim man in the 60s-70s, there was so much more going on around him that isn't going to happen to McGregor or Khabib or Canelo today.
People have made good points too, now it's an age of streaming. Back during May-Pac, and definitely every Mayweather ppv before that...streaming was not as big as it has been in recent years. I watched Hatton over a friends house in 2009, we were all young and no one had a clue about streams, they didn't even exist I don't think or were rare/underground.
It says something that the 2nd highest PPV ever in boxing was Mayweather-McGregor and it was 2+ years into the future where streaming was more prevalent, and close in numbers (and yeah fuck off we're not counting the bullshit free tv Ali numbers).
Sorry for along ass post, but jeez...is this a boxing circle jerk? No Boxing has clearly been dying, and the UFC has pretty much surpassed it. That's facts. The most popular boxing star by far is Mayweather and he hasn't fought a real fight since 2015.