Deadpool - Easy choice.
Cap Winter Solider - Scott Pilgrim is good but Winter Solider is one of the best in the MCU.
Kingsman 2 - Never saw the other one so this is easy.
Guardians 1 - I'm sad because I loved V for Vendetta but Guardians was a hit out of fucking nowhere. The music, comedy, and everything just fucking ruled.
Spider-Man - I know I'm in the minority (only one) but I'm obviously biased. Spider-Man was also a fantastic movie. Willem Dafoe as the fucking Green Goblin. Fuck. It was fantastic.
Spider-Man Homecoming - This was difficult. They're both fantastic movies but...well I like Spider-Man more obviously.
X-Men 2 - Again, in the minority, but Guardians 2 wasn't as good and this was one of the best X-Men movies.
Cap Civil War - Another best of the MCU. Russo brothers...these guys fuck.