Its nice in theory to think that we are there but the top trainers in sports like kickboxing and boxing are vastly more refined due to the years of work put in before them. MMA is not at that level which is why guys like GSP still seek out the likes of Freddie Roach. It will be a long time before MMA is at the level many fans would like to believe the sport has reached. The other problem lies in that different physical traits and abilities as well as the other skills they possess as a fighter. Brock Lesnar is never gonna be throwing head kicks, his body type is better suited to traditional boxing. We will see mma striking develop in its own right but they will always remain ties to the traditional arts and they will use those to refine and perfect them on a fighter by fighter level.
As for the best, I would say you need a combination of boxing technique for your hands, Muay Thai leg kicks and the Muay Thai clinch would be the ultimate if you could combine all 3, which Anderson Silva has to some extent.