Reasons I love Mobile Suit Gundam
1: First anime show to have robots that weren't superheroes. Even though other mecha shows have come along and outdone Gundam for realism, this show laid down the groundwork for them, and made their production possible.
2: Casual violence. Gundam creator Yoshiyuki Tomino creates action scenes where everything from beam sabers, massive robot hands, and even offscreen weapons shots can destroy objects. Other shows do this true, but Tomino does it in a way that catches you off guard. He has no buildup, no dramatic pauses in the animation before a character dies or a mobile suit blows up. The death/destruction simply happens and the action moves on, because there are always more enemies to fight.
3: Characters. Each character grows up and develops, even Amuro. Amuro turns from a cranky spoiled kid, to a young man who bears up better under pressure. In one episode he even gives water to a wounded enemy soldier. No big deal is made out of it (no moral debates in his head, no dramatic pauses of should I or shouldn't I). He just goes ahead and does it. All the other characters are so good, particularly the complicated Char Aznable, that every non-Universal Century Gundam series has basically copied them, changing only the character designs.
4: One heck of an ending. Anybody a Star Wars fan out there? How about Saving Private Ryan? You'll see a final battle at the end that combines the high-tech combat of Star Wars with the grunt beach landing battle scenes of Saving Private Ryan.