As I pointed out in my previous post, a strong, memorable Big Bad has always been Marvel's fatal flaw. Thanos was the exception that proved the rule. Hela was great but, as you pointed out, it was just one Asgardian fighting another.
The MCU also has a bad habit of making even the better Villains one and done. Red Skull had one film in his prime, then disappeared for seven years. And in his next appearance, he's little more than a ghost. Hela was fun, but there's no indication she'll return from being destroyed along with Asgard. Ego's dead, the Mandarin turned out to be a Troll job on the level with Bettany's, "surprise cameo" and the less said about Malaketh, the better.
Great points as usual.
I think actually though that the MCU has improved on villains over the years. There are movies like Iron Man and Doctor Strange where the selling point is the awesome hero's journey and the villains pale in comparison and are lackluster even though they are played by great actors.
But I think of Hiddleston's Loki who was a standout in as early an MCU movie as Thor. Great nuance to the role and that's probably why they keep bringing him back. Ton of charisma too. THanos- it goes without saying- best villain in the MCU so far. Executed near perfectly.
Other ones that I have really liked:
Kurt Russell as Ego- as you said, one and done, but awesome performance in an underrated MCU film in my opinion. Russell kills that scene with the big reveal of Ego's master plot. It's actually a pretty horrifying scene when you realize what he's been up to- I think of it as similar to Sam Jackson reveal at the end of Unbreakable- all this destruction and killing all for the purpose of finding "the one."
Gyllenhaal and Keaton in the Spidey movies. People seem torn on these films but I think that the new Spider-Man movies have absolutely had great actors playing damn solid villains. Tooms being a criminal driven by a desire to provide for his family was interesting. Keaton knocks every performance out of the park typically and that was no exception. Made a villain like Vulture that has never really resonated to me far more interesting than he otherwise might have been. Ditto for Gyllenhaal who didn't hit a wrong note- from the tragic hero facade to the scumbag with delusions of grandeur.
Blanchett as Hela- the look and the charisma that Blanchett brought to the role made a potentially one-note character a scene-stealer and a memorable part of an even better movie.
Daniel Bruhl as Zemo- great performance and a change of pace type of villain. Bruhl is an excellent actor and he left his mark.
Michael B. Jordan as Killmonger. I enjoyed his intensity in the role. He was a ruthless p.o.s. and Jordan sold that well. There's that one scene where he shoots his girlfriend just to get to Andy Serkis. Brutal, cold-blooded stuff. I thought the first fight scene between him and Boseman (RIP!) was great as well.
Lee Pace as Ronan. Really had an awesome look, voice, overall demeanor in a really good MCU film in Guardians. Guardians easily could have only had the stuff with the core team going for it and still been a lot of fun but the fact that Ronan was a damn solid villain helped put it over the top.