Kiseijuu, Shingeki no Kyojin Recommendations
Despite the temporal distance, both mangas are very similar by the feelings that they get.
Violence and particular design must be surmounted, because it's beyond that is situated the real treasure : a beautiful thought on the human kind.
The heroes of both series, although different in motivation, have the same goals, and that is to exterminate the creatures that push their mankind to fear and despair with the help of their special powers.
But there is more than that; both series revolve around the question of one's humanity. While SnK takes this on a subtle approach, Kiseijuu is direct to the point it is the manga's main theme.