You can only recommend 10 MCU flicks for someone to watch before Infinity War
Let's say you meet someone who has never seen any of the MCU films but wants to be caught up with the Infinity Stones storyarc in preparation for watching Infinity War. You can only choose ten MCU films for them to watch. What ones do you choose? Here's my list (keep in mind, this is NOT a top ten favorite MCU movies list but a way to convey the most important story elements):
Iron Man 2 - Intro to Black Widow, SHIELD, War Machine, etc.
Captain America The First Avenger - Intro to Cap and the Tesseract
Avengers - Intro to Thor, Loki, Asgard, and the Avengers team
Winter Soldier - Intros Falcon, fall of SHIELD, reveals Bucky is Winter Soldier
Dark World - Intros the Aether and the concept of the Infinity Stones
Guardians of the Galaxy - We get a backstory of Thanos, intros the Orb, and talks more about
Infinity Stones
Age of Ultron - Reveals Loki's scepter has the Mind Gem, more Infinity Stones stuff, intros Vision and Scarlet Witch
Dr Strange - Intros magic side of MCU and the Eye of Agomotto
Civil War - Avengers split, intros Spider-Man and Black Panther, War Machine is crippled
Black Panther - I assume it introduces the Soul Stone (if it doesn't I'll replace it with Ragnarok)