In anime you have a bunch of decisive groups and tastes forced under one umbrella. So there are a lot of genre classes due to certain fan groups being mixed when they have no business together

But specifically...

Shounen is pretty divisive here. Some people love One Piece and Naruto, others can't stand it's particularly strong stereotypes.

Cute Girls doing Cute things. Accessories for these sell, so they're pumped out. The market glut gets people.

Culture v. Nonculture. I don't know what you to call this, but there are a lot of argument over waifu jokes and the lot. It's basically people getting upset over the the stereotypical anime culture embarrassing them.

Sexual material in general. Japan has a much different view of sex, and people in the west have a problem with escaping their Puritanism.

I don't know if it's a particular divide here, but there are a lot of people here who think that watching anime somehow makes them deeper or different ("How has anime changed your life" threads) and I just want to slap them fucking silly for being so self aggrandizing. (It's cartoons, from a particular set of islands. That's all)