Anakin Skywalker/Darth Vader has easily been the best treated by the Disney canon, including his role in Rogue One, Star Wars Rebels, Jedi: Fallen Order as well as Jedi: Survivor. Plus Anakin got more time in Clone Wars Season 8 and Ahsoka all being pretty cool. I even think Vader was the best part of the Obi-Wan Kenobi show. The best parts of that show were Ani vs Obi.
That said, Yoda has gotten more lore in the High Republic era, and as a huge fan of The Last Jedi, I think Yoda's scene in that movie is easily one of the best in all of Star Wars and captures his character from the original trilogy better than anything in the prequels (despite enjoying those).
I'm of the opinion that Luke was done well in The Last Jedi as well, as hot as that take may be. I think giving the weight of the galaxy to a single guy who finds out that despite everything he's tried, he's still failed, it a very realistic route to take. Think, in the old EU, how many times did Luke turn evil or get cloned and turn evil, or have evil tendencies, or have his family turn evil. Luke has never been treated well by any supplemental material because, as a character, Luke just kind of sucks. He works for the OT as simple movies, but I think the way Disney took him is the best way they could've. I'd rather see the Luke we got than some unbeatable God amongst men who does no wrong and is 100% perfect take on some bad guys single-handedly. That'd be lame as hell.
Overall, I think the only character who hasn't at least gotten some interesting stuff done with them that isn't better than the old EU garbage is Boba Fett. I liked him in Mando season 2 and am cool with him being a changed man, but Book of Boba Fett just kind of sucked.
I know toxic fanboys online like to whine and winge about the "state of Star Wars" but really, it's no different than it has ever been. No, people didn't love the sequels, but they also hated the prequels for 10+ years until the sequels came out and gave something new to hate. Yeah, Boba Fett and Kenobi were disappointing, but so weren't the countless EU stories where Han and Leia's kids turned evil or Luke got cloned into the villainous Luuke. Star Wars has always had bad, always will be bad, and we should just embrace it instead of crying.