There's a few bits of content in EC that's a bit explicit, so I go for either 15+ or 18+. It makes sense.

I think it depends on the country. For example, Mirai Nikki has ridiculous amounts of nudity and violence. It is raked R15+ in Japan and 18+ in South Korea. So I think EC anime would be ranked 12+ in Japan and 15+ in South Korea.

15+ seems appropriate

15+ works

15+ I think too (although in France (sweet home) I rather feel that it would be 10+ XD (like all the unknown films are 10+ while sometimes it's hot (maybe not those containing sex but gore))

I would definitely say it would rank 18+ in western countries since there's a lot of sensitive content such as murder, rape, incest, etc.

18+ in USA; 15+ in Japan.

In USA it's probably going to be mostly because of the incest and cannibalism.

That's true