 If you liked Re:Zero kara Hajimeru Isekai Seikatsu |  ...then you might like Shingeki no Kyojin Season 3 Part 2 |
The characters never break character in either series, it always feels real and serious throughout. Re:Zero takes place in a fantasy world but it has a high sense of believability and realism, the way AOT does. The MC is an extremely cool character instead your typical "normal dude". The show has very real, dark, impactful violence and emotion.