Muv-Luv Alternative

MLA was the main inspiration for AOT. You can see too much similarities between the two series (characters, themes, universe, politics etc.) 

MC isekai-d from our world to a parallel mecha-apocalyptic Earth, met alternative versions of people he knows and claimed a harem of kawaii girls. Simply put, Dual is a spirital ancestor of Muv-Luv Unlimited/Alternative, but without their deepness and drama. 

Both have giant robot of course and are fighting to protect earth from complete distruction. 

Mecha , same alien vs human story .. it's like attack on Titan + darling in the franxx 

Human vs Alien story, Mecha combat animated in 3DCGI. Humanity leaves the earth, very similar to Alternative V project. If you liked Alternative, surely you will have a good time with Sidonia no Kishi. 

Similar premise. Humanity is on the back foot fighting against insect-like (building hives and all that) alien invaders with a fish out of water main character. Both feature "realistic" mecha inspired by real life military. 

I can't believe no one actually compared 86 to Muv Luv Alternative. Reasons why they are similar: - Humanity is in the brink of extinction - Humanity has created mechas to combat a threat to humanity. - The BETA and Legion have very similar properties - some of them are mindless creatures, while others are smarter and act as commanders to their fellow creatures (in 86 they are known as Shepherds, in MLA they are known as the Superior). - Some types of Legion and BETA are similar to each other: Lowe (86) is similar to Fort Class (MLA), Stachelschwein and Biene (86) are similar to Laser Class (MLA), Zentaur (86) is similar to Carrier Class (MLA)  read more 

Similarities - Both MCs are students at a military/cadet academy - Both MCs have a female harem - Both MCs use high performance mecha - Both worlds have high levels of technology Differences - in Infinite Stratos only women can power mecha VS Muv Luv anyone can power mecha - in Infinite Stratos there aren't any unknown alien lifeforms that attack earth - IS feels more like a school/SoL VS Muv Luv feels more like a dystopian, Sci-Fi - MC in IS doesn't isekai VS MC in Muv Luv isekais into a parallel universe into the past