This is a really hard question to answer, because the sport is in a constant state of evolution.
For his time, nobody dominated like Royce Gracie, who you could compare to Don Hutson in that regard. But in reality, it could have been any number of BJJ practitioners doing the same things, it's just that they chose him as the ringer for UFC 1.
The most well rounded and dominant fighter I have ever seen in GSP, followed closely by Anderson Silva, and then Fedor. What sets GSP apart, is at his peak (right now), he doesnt even lose rounds. He doesnt even lose parts of rounds. Fedor, even during his amazing run, was dominated for stretches. Silva was dominated by Sonnen for 4 1/2 rounds. GSP was flash KO'd by Serra and hasnt been challenged for a single second of his prime since.