Iron man. The ending was really a standard heromovie ending, but besides that. What's not to love about this movie?
Iron man 2. Expected it to be less good than 1, but it came pretty close. I hated Iron man 3.
Thor . It was a new character, I didn't really know a lot about Thor. It was a bit darker than the other movies. It surprised me. Loved it.
Thor Ragnarok - didn't like it the first time at all. It was so extremely different from Thor 1., To lighthearted, to much humor etc. After rewatching it, I realised that it was actually pretty good and funny.
GotG. - Fun, visually very good, action sci-fi. Really different from the other movies. Origin story.
GotG2. Again - didn't expect it to come close to first, but it did. The only series that doens't have a weaker movie. But with only two movies, that might change in a couple of years.
Doctor Strange - I really like the origin stories. this one is no exception. I think captain america and Hulk are the only ones, that aren't good. Althoug still watchable.
Captain Marvel: Didn't like a couple of things about this movie, but it still was really fun. See might be too strong for the Marvel movie Universe, so I'm wondering how they are going to fix this.

But my two favourites:
Captain America Winter soldier- the only scene I thought was a bit strange was the fight between Cap and the guy on the boat that kept getting up. I thought he had to be the winter soldier, but he was just a guy with a body of steal? Besides that, this movie had everything,A good spy story, a good evenly matched opponent for cap, and the Hydra/Shield story. Good action scenes.

Civil war - was a bit of a disappointment for me. It felt like an Avengers Light/another Iron man. Should have a bit more drama, they kept it too small.

Avengers Inifinity war - They really made everything fit together perfectly. On his own, it would have been a strange movie, but as an movie that connected all of them together, it was really perfect. And still all the characters kept their own style. And the movie had a origin story about Thanos. So, that's always good :p And unlike Civil War, it really felt they were fighting for something real and big,. Besides that, the visuals were really good, and the new places seemed to be real places (loved the scene/planet with the soulstone), especially compared to the latest Star Wars, where the new cities/places didn't really connect with me.

It made me think Endgame was going to be the perfect movie, again connection all the movies perfectly and working to a climax of enormous proportions. But they went for a really different style, and in my opinion, they shouldn't have done that. They didn't bring the time traveling in a credible manner, I hated the looks of professor Hulk. His evolving to professor Hulk could have been a movie on it's own, but now, he was just there from the beginning, like wtf. And it was too much of an Iron man, Captain America movie, It should have been an Avengers movie, with bigger roles for an all destroying Hulk and Thor. The endbattle really didn't work for me.

Logan...Greatest superhero movie....ever...I actually cried in that.

Endgame - Because it absolutely lived up to my very high expectations to be the culmination of all the entire franchise. Now, the film definitely has its flaws and most of them relate to Time Travel. But it hit all the right notes in all the right places. There were character arcs that got satisfying conclusions like Steve and Tony burying the hatchet, the Banner/Hulk dynamic.
There were moments that got me laughing hard:

Moments of pure awesomeness:

Moments of pure shock and/or heartbreaking sadness:

And moments of tear-jerking happiness and satisfaction:

Avengers: Endgame isn't just my favorite MCU movie, it may very well be my favorite movie, period.

winter soldier my favorite, really enjoyed the story.

Even though it is not an MCU movie, I totally agree with you that is is in fact one of the best superhero movies ever. I was SOOO disappointed that Huge and Sir Patrick were not even nominated for their respective performances along with a Best Picture nomination that year.

Indeed that was one if not their greatest performance in the X-Men films. The movie actually went to places Superhero movies rarely go to.

Guardians of the galaxy, cant wait for the third installment and I'm really hoping Thor has joined them.

I honestly haven't seen one that I like.

If the X-men films are to count, then it will be Logan followed by First Class and the two Deadpools.