Think about this fact:
The Canadian Olympic wrestling team tried to recruit GSP to wrestle for them, A SPORT IN WHICH GSP DIDN'T TAKE UP UNTIL HIS TWENTIES. GSP was the best wrestler in MMA in his prime, and nobody had a quicker first step than he did. This was evident in his incredibly fast double leg shot and his elite striking.
Most great collegiate wrestlers in America take up the sport as early as five or six, Middle School at the latest, and most of those guys never make an Olympic team in their lives.
The fact that GSP was basically an Olympic calibre athlete in a sport which he didn't even spend training full-time and took up his twenties shows that he is clearly the best athlete in MMA history.
I know people are obsessed with roided guys who have big muscles but GSP has a great physique himself that is functional.
Plus, on top of his fast-twitch explosiveness, he also had some of the best cardio in MMA. Something that is very rare amongst explosive fighters
When you combine top-tier genetics with hard work and a high IQ, GSP is what you get: the best MMA fighter ever.
Best athletes:
1. GSP
2. Lesnar
3. Rockhold
4. Romero
5. Garbrandt