For myself, there's two pieces of anime media that I just don't understand the appeal of: My Neighbor Totoro and Evangelion, for different reasons.
I like a lot of Ghibli's work, like Princess Mononoke and Spirited Away, but I found Totoro mind-numbingly boring. It felt like 80% of the movie was them doing housework, followed by some conflict slapped on at the end. Beyond the typical Ghibli art style, there's nothing compelling in the whole movie.
I also kinda hated Evangelion. I thought the philosophy, one the the aspect's of the show that get's the most praise, was something out of a Philosophy 201 elective. The pacing was uneven, even for an anime, and the show's treatment of every single female character was straight-up gross, which is made even weirder due to the fact that half of them are 14.