Here in Europe it's definately Wladimir Klitschko. That's also because Vitali is known as Ukrainian politician.
It definitely depends on the demographic. In europe it's probably Wladmir and Joshua. Across in the states it's probably mayweather and Canelo. In the middle east it's probably Amir khan and in Asia it's no doubt Nobuhiro Ishida.
After PAC, it's hard to say if anyone is really mainstream. I'm not including Mayweather because he's "retired." To the casual fan, it's Canelo and then Cotto. But most casuals I've spoken to consider GGG the boogie man in the sport.
Is Amir Khan really popular out there? I used to think that Khan is the only one to think that he is popular anywhere.