There is no way one can equate like for like in any sporting event or achievement,just one to look at, ALI there's no heavyweight now who could hold a candle to him in the ring.....but I would say Marciano was as good but you have two guys doing the same thing with differing styles and a few different rules too........
Arkle and Flying-bolt were the best we ever saw in their time! One must again try to put it into prospective like for like re; the fence sizes which have been reduced and altered over the years they ran on ground that was on a par with today's, but that now gets cancelled because you now have all these p-c people and animal rights associates you never had those in the good old days, or they were few and far between......
Yes over two miles you will find the latest star [Master Minded] a brilliant fencer and yes you may think he is the best on four legs[I personally am very impressed] but you cant relate like with like, and era with era...............