#6 Daniel Bryan

Daniel Bryan is one of my favorite wrestlers of all time. He's an amazing technician and storyteller in the ring. He can also deliver any type of promo from an extremely passionate promo stating why he's an A+ player to an emotional retirement speech. And then he can berate the WWE Universe for being wasteful as the heel Planet's Champion.
Like Natalya, although with a brief period of retirement mixed in, Bryan has been a part of WWE for more than a decade. In his case, he was a part of NXT when it was a competition back in 2009. During an eventful career, he's won the WWE Championship four times and the World Heavyweight Championship once.
Bryan is such a valuable performer because although he has had main-event runs, he has also put over younger Superstars like Murphy, The Fiend, Roman Reigns and many others. For a Superstar his age to be willing to do that is not unheard of but a sign that he cares about the craft and its future.
You can also add the Yes Movement to his many accomplishments. It's spilled out of the WWE and into pop culture at college basketball games and other events. He's had a huge influence on the WWE product and without his storytelling, matches wouldn't be nearly as impactful.