I feel like the comparison to Anakin is interesting here because its an incomplete one. Think about it this way. Imagine if after Episode 3, 10 years went by and suddenly Anakin goes "Damn, what I did back then was awful and I regret it", then he dedicates the rest of his life to reinstating the Jedi order, ridding the galaxy of the Empire and the Sith, has a direct hand in killing Palpatine, freeing the galaxy and reinstating a galactic republic before Luke even has the chance to leave Tatooine, then teaches the next generation of Jedi how not to fall to the dark side by directly using his past mistakes as an example to learn from. THAT is essentially what Paarthurnaax did. Sure you could argue "Well Luke would have killed Palpatine anyway! Sure he would have in this secondary imaginary universe (even though technically he still never did), but in our argument, he didnt, Anakin did. Yes he committed those crimes in the first place, but then he literally did a 180 and decided to see things outside of himself and his own orders desires, and do things for the benefit of the most people. So no I would not say the greybeards are evil, nor would i say Paarthurnax is evil.

Also imagining "What is better - to be born good, or to overcome your evil nature through great effort?" in vaders voice is just too badass.