In MMA who has the best Mount

Who has the best mount in MMA or sport grappling

In sport grappling it's hard to imagine being in a worse mount than

yes he looks awesome

Rickson - see Fujita fight

In all my rolling, no one came close to feeling of total helplesness that you feel when Roger gets mount. You try an elbow knee escape...his leg doesn't even move an inch, you try to bridge, he feels like's like being in quicksand, the more you struggle the worse trouble you get into.