I think Canelo will beat him. Neither have looked brilliant in their last couple of fights but I just think it's a timing thing and where as Canelo has fought fighters way out his league and not looked brilliant I think it's age catching up with GGG now.
Re the Mayweather stuff I think he's a great boxer, I'm not sure where he ranks on an all time great list, I honestly don't really get lists like that. I admire the effort and thought that goes into them but lets be honest...a fighter who fought in something like the early to mid 1900's it's hard to give a fair opinion of surely? There's no chance you can give a fair reading on people like that.
Look at Floyd for example as he's the fighter we're discussing, his CV includes Castillo, Hatton, De La Hoya, Marqeuz, Moseley, Cotto, Pacquiao and McGregor that's some of the best boxers he could of fought and yet the common counter argument is they were all (or most of them) were way past their best. By then putting someone from the early 1900s in a list as an all time great you're suggesting that you know their history, you know their opponents history and know their opponents weren't old/overrated/past their best/not that good to begin with. To me it just seems an odd way of judging something but each to their own.
Basically what I'm saying is people will judge on record and what they read etc and surely that's not a fair way to give an opinion. In years time when Floyd is long gone for example and he has a record of 50-0 that includes the names above people will automatically end up putting him on a list of P4P All Time Greats and no one would argue. People look back fonder on history than they do what is happening in the current.