ALL judgements about ANY art form, including music, are subjective. That is... If you like it, it's great. and if you don't, it's not. No amount of qualification can "prove" that one person is "better" than another. The audience can't be convinced that someone is better or worse than any other person, except by "what THEY like".
If "speed" is the only issue, then that's something that can be mechanically calibrated and measured. But... It has NOTHING to do with music or art, in my opinion. I consider the issue of "fastest" to be a very shallow barometer of musical integrity. (although it can certainly be exciting, at times)
Buddy Rich, along with the many incredible writers he utilized, and the musicians in his bands, gave this planet a HUGE number of tremendously exciting live and recorded performances, which you can buy and listen to, and make your own judgement.
In my opinion, Buddy, his writers, his recording methods, (mostly live) and his players,have produced some of the most timeless, hip, sensitive, technical, "firey", emotional, "funky", "swinging", dynamic, and historically important music ever performed by anyone. Opinions will vary.... That's mine. It's one thing to "play a thing". It's quite another to INVENT it. And... It's not "what" Buddy played, as much as "how" he played it.
If you would like to hear some live (and unpublished) recordings of Buddy and his bands (free) visit my page at http://www.mikejamesjazz.com/br_clips.html
I feel very lucky to have experienced many of those beautiful performances. To this day, Buddy's performances strike a certain nerve with me that no one else approaches.