If you check Adam Driver's (Kylo Ren's) background you'll see he's a former Marine who's done a LOT of good with his recent fame. Plus check him out on YouTube when he hosted Saturday Night Live. He did an "Undercover Boss" as Kylo Ren that's really funny!
Anyway - what makes ANY villain a good one is a clear, understandable motive combined with power. Darth Vader is a good villain because you see him destroy things the heroes love (Alderaan) and you know he's capable of destroying everything.
Some have said - and I agree - that one of Disney's greatest villains is Lady Tremaine in 'Cinderella'. She's evil, but it's not a cartoony evil; she's calculating and shrewd. She has no superpowers but she manages to hinder and harm Cinderella just by saying things to the stepsisters. She's a perfectly ordinary person, probably even admired in the community. She gets away with a LOT of evil that has nothing to do with blowing up planets or stealing secret formulas. That's what makes her
really scary - her villainy is very human.
An axiom that I think is very true is "every villain is the hero of his own story". Thanos just wants to bring balance to the galaxy. Judge Frollo just wants law and order. Scar just wants the same respect his brother Mufasa gets. Sid has the same imagination Andy has, it just runs in a different direction.
One of Pixar's best movies is "Finding Nemo" and the only character close to a villain in that movie is Darla - and even she just wants a pet fishie. She's simply too undisciplined to know that her 'affection' is harmful.
So, there's my answer. I thought Syndrome was a pretty good villain, but my favorite is Gaston from Beauty and the Beast. Clear motives, HUGE jerk, and everything that happened to him was his own darn fault! Plus he had a great baritone.