Kyoukaisenjou no Horizon, Hundred Recommendations
-Both series are about wars and battles,the action can be pretty ok sometimes
-Students studying at a battle academy,mecha stuff,magic,special abilities...
-The main heroine and the hero share a dramatic past (*flashback alert*)
-A community living on a huge ship (but in KSNH the "ships" are floating
-Well,you know... fanservice and...a lot of pervy things
Overall these two animes are a lot alike. There are also differences but they don't really matter because the atmosphere is pretty much the same. (^-^)