Mobile Suit Zeta Gundam, Shingeki no Kyojin Recommendations
Both shows have people fighting Titans to free themselves from oppression. The only difference is that AoT is human and ZG is mechs. Main chars are different in terms of aspect.
SNK is literally the dark fantasy version of Zeta Gundam.
In both series, you have:
-Humans fighting against Titans
-An angsty teenager (Eren/Kamille) who wants nothing more than to kill all Titans
-A wise mentor (Dot Pixis/Quattro Bajeena) who recongizes the potential in that angsty teenager
-High body counts in both series due to the atrocities committed by the Titans