Marcelo and Rafa are probably P4P best. I'd pay good money to see a superfight between them.
On a crazy note, I've been to about 4 mendes bros seminars, and in most of those, they lined everyone up by belt level, and tapped down the line. And when that line was done, they circled back and tapped down the line again, until no one was standing.
Granted there were only about 10 brown and black belts in a group of 40 grapplers, they didn't really look any different regardless of size or strength. They were that damn good. To see gym owners get tagged in 30-40 secs, I was like these guys are for real.
It would be a treat to see Rafa x Marcelo, maybe even a passing of the guard, no pun intended.