I think recent MCU has better villains than it’s given credit for – Killmonger, Vulture, Hela, Ego, Mordo, Zemo, Loki, Pierce – it’s bigger problem is that it keeps killing off villains so that they’re one-offs and can’t develop over time.
As for the X-films….Magneto was good but they really over-used him, and Stryker is less interesting without his theological costumery. But how do you get Oscar Isaac, one of the best actors working today, and so completely waste him? And while I love Peter Dinklage’s work, I can’t say that his Trask was particularly engaging either.