[member="Samka Derith"]
Well, to be fair, there's not a lot to current Canon: most of the material that shows the Sith as something other than 'pure evil' exists in the Legends material. True, you still get your mostly-evil people (Marka Ragnos, Exar Kun, Naga Sadow etc), but the closer you look (particularly when you see what Vergere and Lumiya have to say about the Sith), the more you realise they're not evil: they're pragmatic survivalists with a superiority complex. They don't hesitate to kill or destroy if they see that as the way to do what needs to be done in their eyes. You also notice that the Jedi tend to be stagnation-maintaining agents of a corrupt government, trying desperately to keep things peaceful and quiet (which is absurd) while never having the guts to step up and do what needs doing to fix the aforementioned government. Unsurprising that the Sith resort to desperate measures to try and resolve the situation!
By the by, what Lucas intended in the Prequels is pretty much what we got: a mess. But the clearer observation you get from watching the films and reading the books is that the Jedi ended up being a peaceful Order utterly challenged and destroyed by war, which they were never supposed to participate in. Even their role as 'Keepers of the Peace' was a perversion of Jedi philosophy: they were forced into such a position because they were the only ones who could. They were in over their heads, and positioned that way by a Sith Lord who knew they were the biggest obstacle to changes in the Republic. When the Jedi were gone, so too fell the Republic, and in ushered the Empire: peaceful, disciplined, orderly, although sadly also xenophobic and oppressive. What you can recognise about the Jedi, though, is this: they believed in the system that had already failed them hundreds of times, and were the only thing preserving it. That's what you call both dedicated and wholly misguided!