Intro to Gundam: What to watch first?
1. Mobile Suit Gundam 0079: The OG. The story is great, and it made Yoshiyuki Tomino the legend that he is right now. Animation/Sound can be a bit dated, but at least it is chock full of memes.
2. Mobile Suit Gundam Iron Blooded Orphans: The newest of the "alternate timelines". It tells a grand story through 50 episodes based on the same basic Gundam setup and skeleton. However, it is a totally unique story overall and stands on its own apart from all other Gundam series. Written with Mari Okada of Kiznaiver and Anohana fame. One of my favorite Gundams of all time, it follows the story of a rising leader/captain as opposed to the ace pilot.
3. Mobile Suit Gundam THUNDERBOLT: A side story from the original Gundam timeline, it can be watched without any other experience even though it references a lot from other shows (mainly the original Mobile Suit Gundam listed in 1.) Clips like these are my favorites to show that this is one of the most beautiful shows of all time. The Jazz OST is unique too. I recommend watching the compilation movie that connects all the episodes together called Mobile Suit Gundam THUNDERBOLT: DECEMBER SKY,
4. Turn A Gundam: A fan favorite alternate timeline show. It's a bit older, but the animation is beautiful. The Gundam has a mustache. Also dat Yoko Kanno OST is fire.
5. Mobile Suit Gundam UC (Unicorn): Not recommended but some people enjoy it as their first Gundam. It is IMO the most beautiful Gundam ever has been and every will be. The Hiroyuki Sawano OST is probably the best he's ever made. The mechs and fights are something completely out of the world.