*1. Captain America: The Winter soldier - A well paced action adventure with an interesting mystery and the best fight scenes of any MCU movie. It also evolves the characters in a meaningful way and has a big impact on the greater world of the MCU.
*2. Guardians of the Galaxy - Wonderful characters, design, music, humor, pacing, action. etc.
*3. The Avengers - Good balance between the characters, fun action and humor.
*4. Iron Man - This changed superhero moves and started the whole MCU, also Downey Jr. brings Stark to life, and the movie is very re-watchable.
*5. Ant-Man - Imaginative visuals, great effects, interesting characters. The only real downside is that the villain is basically Obadiah Stain part 2.
*6. The Avengers: Age of Ultron - More good balance between characters, a better than average villain, some cool new characters, and a suitably epic evil villain plot.
*7. Iron Man 3 - I don't get why so many people dislike this movie. I get that they didn't like such a great actor playing a buffoon, but I really enjoyed the twist. The movie also had some spectacularly directed action sequences and funny lines.
*8. Captain America: The First Avenger - Pretty solid action and great overall look. The downsides are that the action sometimes looked a bit flimsy to me, and the the story felt a bit rushed. It did have one of the better MCU bad guys though.
*9. Thor - Cool design, funny Thor-earthling interactions, and the best MCU villain.
*10. Iron Man 2 - Some cool action, albiet it felt a bit shoe-horned. It introduces Black Widow who is a great character, but she doesn't have much interesting to do. Whiplash is an underrated bad guy.
*11. The Incredible Hulk - A watchable movie, but nothing really memorable.
*12. Thor: The Dark World - I barely remember this one.