One of the biggest issues I have with superhero movies is the one and done nature of their villains. Reeve's Superman kept Luthor around, but he took a backseat after the first film. Batman killed off Joker. Nolan's Batman tried to tie Begins and Rises together. Pretty much every MCU main villains were one and done.

So, whose Trilogy would you like to have seen with a full 3 movie epic hero vs arch villain arc? Batman vs Joker? Iron Man vs the real Mandarin? Captain America with his Howling Commandos vs Red Skull?

The Batman might do it, since they didn't do the typical "main villain gets killed in one movie" and the clues that Riddler would be back.

Actually - Iron man vs Obadiah would have been fine. I liked how Obie was great friends with Stark Sr and how he sort of took Tony under his wing early on. Its a classic yet interesting relationship, IMO. The Mandarin didnt do much for me. And, wasnt Guy Pierce the real villain? . I actually didnt mind Justin Hammer & Micky Rourke though, fun stuff.

Still - Id take an Obie vs Tony for three movies.

Speaking of Tony, I think you can feel pretty safe that RDJ is gonna be Dr. Doom for a while.

I mean two major MCU villains that weren't one and done were Thanos and Loki.

I do wonder why there's such a sense of finality to the bad guys in these films as opposed to locking them up/having them disappear for a while then engaging them again. Maybe the actors don't want to make any kind of commitment? They usually do get actual name actors for a lot of the major villains (as opposed to a lot of the heroes who they sign to multiple movies) so maybe it's all one and done as far back as Nicholson.

I know Age of Ultron is not held in high regard but IMHO Ultron should be an ongoing menace, same with masterminds like a (real) Mandarin, Ra's Al Ghul, Luthor, etc.

Honestly I’d prefer if the villain was around for longer than that. They could float in and out of the franchise from lead to cameos. Luthor, Joker, Doom, Galactus, Doc Octopus, Green Goblin… the list goes on.
One and dones will still exist as they should.

I was talking more about Hero specific villains that are known as their arch enemies. Loki was a special case as he was and wasn't a villain.

Even so we got two full movies with him as the villain (and then much more)

If we're talking like the same antagonist across multiple solo films, I think unlike comics that's just a lot harder to do since movies take so long to make unless the character is just more in the background like a Thanos or a Darkseid or something. With Loki it was vs. Thor then vs. the Avengers which I think mixes it up enough. Then if the relationship evolves where they have to team up for a common threat that can work like Loki or Magneto, where the antagonist of the next solo film is at least different.

The problem with that in today's market is that there's no guarantee that whatever franchise will last long enough to see it through.