Top 2 in Top 10 best fantasy anime similar to Attack On Titan you can't ignore.
God Eater Fiction Anime Trailer
God Eater is the best sci-fi anime similar to Attack On Titan, as well as a post-apocalyptic anime that ran from 2015 to 2016 with 13 episodes. Set in the year 2071 in a country called the New Asian Alliance, an organization called Fenrir helps protect people from monsters known as "Aragami", they use Special weapon called "Arc of God". This point is quite similar to Attack On Titan.
This anime is actually based on the video game of the same name produced by Bandai Namco Entertainment, which supports play on PlayStation 4, PSP and Windows. The game was released in Japan in 2011. So, if you were intrigued by God Eater, you should also learn about the game of the same name.