Although, now that I think about it, I've watched this old one called night on the galactic railroad and really enjoyed it, so that could be my favorite?
I wish I was older so I could say something more sophisticated and cultured. I thought Scissors Seven was really funny, watched it in like 22/2021? Anyways it has a special place in my heart.
I started with Neon Genesis Evangelion and it's always been my favorite, it's far from being the best piece of media (or even tranime) ever made, but it struck a chord with me since I was 14 when I first watched it.