Getting a buddy into anime

Hey everyone I recently convinced a buddy of mine to watch AOT and vinland saga. Problem is, they’re rather a serious individual so I am looking for shows that would fit the criteria of someone who loved those 2 shows.

I was thinking of FMAB but maybe that is too unserious for them? I am kinda lost which is why im asking here. They’re looking for something with a deep story, which doesn’t really help me in my search at all 😭.

Any help would be appreciated!