Who is the greatest mma fighter of all time?

i am not a pro fighter but have black belts in 2 styles and have boxed for 16 years. i don't think just because someone is a fighter, their opinion necessarily holds more weight than a fan, unless that particular fighter has fought all the great mma fighters in history. that being said, matt hughes did put together a great string of victories, royce is a legend, i love couture but he has too many losses, and anderson and gsp have to be considered if they keep winning, even though they also have losses.