#1 Brock Lesnar
Brock Lesnar had the world at his feet during his first run in WWE in the early 2000s. The Next Big Thing, as dubbed by Paul Heyman at the time, Lesnar won the 2002 King of the Ring tournament.
Lesnar also went on to become the youngest WWE Champion after beating The Rock at SummerSlam. However, The Beast decided to throw it all away to pursue a career in football.
Brock Lesnar only returned to the WWE in 2012 but has easily been the most dominant force in WWE ever since. Barring one exception he has wrestled exclusively on PPV and achieved many feats.
The Beast broke The Undertaker's WrestleMania streaking in 2014 before going on to decimate John Cena at the following SummerSlam to win the WWE World Heavyweight Championship.
The Beast has been a constant presence in the world title picture ever since, including his record 503-day reign as the Universal Champion which he started after defeated Goldberg at WrestleMania 33. He also went on to win the WWE Championship again by beating Kofi Kingston on the FOX debut of SmackDown before dropping it to McIntyre at WrestleMania 36.