there's a lot of reasons tbh. for one, i see a lot of myself in anthy - visually and storywise. it's also rare to see a character who is very obviously south asian in anime, and i love that her character isn't a racist caricature. the victims in the story aren't villainized for being victims, they're complicated and they're messy and their actions are difficult to initially understand or empathize with because they're not perfect victims. obvious and casual lesbian representation done RIGHT is so rare in media as a whole and the way rgu handled both sexuality and gender speaks to me as someone who struggled with their identity for years. i love that utena is proudly a butch, she is genuinely so loving and kind, i love that her friendship with wakaba isn't treated less than, and i love that rgu hammers in the importance of female friendships and the comfort of being yourself with a good friend.
it's so hard to fully put into words, which is why i took a while to answer this (sorry about that ;;;). the short answer would be that it revolutionized my world, really (it really helped me understand that i was a lesbian struggling with comphet). there's something so beautiful about this media that makes it seem like it was made for me, and maybe that's why i like it so much.