You ain’t wrong but most of Marvels villains are purposefully disposable as their films are to showcase the Hero’s, but there have been plenty of good to great villains in franchise spanning 10 years, Bond has the same issue some weak villains some great.
Loki was the MCUs first strong villain.
Personally I loved Sam Rockwell as Justin Hammer the film was over stuffed (but that helped Marvel big time and taught them what not to do, somehow DC must have missed this one) but Sam himself as the arrogant greedy business man/villain was great!
Alexander Pierce, The Winter Soldier & Hydra where awesome in Cap2.
Hela in Thor Ragnorok was pretty bad ass and of course Cate Blanchett was great as always.
Killmonger was pretty strong and nicely developed.
I also enjoyed Ghost in Antman & the Wasp an interesting villain, my daughter wants to dress up as her on Halloween so I might be a little biased here.
Thanos obviously being the best villain to date along with Loki, but I think that’s certainly been intentional to build up Thanos as the ultimate badass, he did whoop the Hulks ass in the first 5 mins of infinity war.