If you liked the Infinite Stratos anime, the Anime-Planet community thinks you'd like:
Both these shows are fanservice vehicles for their cast of well endowed females. Both shows involve the girls all fighting, but Infinite Stratos uses mechs to fight.
Freezing is more explicit with actual nudity. If you're looking for some ecchi fanservice with minimal plot then these are the shows for you.
Infinite Stratos is also very similar to Mashiroiro Symphony: The Color of Lovers. The main character is the only guy in a Female School!!! The reason he joins is he is able to use a machine which only females can use. There is quite a bit of ecchi in this anime but it is in a contained anime. The harem that surrounds the main character is quite alike. You should probably watch the first episode & you will truly be astounded that's a gurantee if you loved/liked this anime
In the not-too-distant future, Earth was attacked by mysterious beings and before long over a third of the world's population was destroyed. Even after bringing to bear its full, united military strength, humanity was unable to repel the assailants and forced into using weapons of mass destruction. This was successful, but the war and its conclusion resulted in the deaths of a crushing percentage of all fighting-aged males, and Antarctica being melted, causing much of the Earth's land to sink underwater. Years later, three young girls - Otoha, a headstrong country girl; Karen, a technical genius; and the highly-disciplined and strong-willed Eika - are being trained to pilot Sonic Divers, weapons being developed lest humanity be caught off-guard once again.
If you'd remove the one male from IS, you'd end up with Sky girls. Sky girls focusses more on the relation between different girls while IS focusses on, well boobies and girls trying to conquer one male.
If you liked one, check out the other.
Ever since Tomoki was a boy, he’s dreamed that the girl he loves vanishes into the sky. However, while he’s convinced it’s just a dream, his classmate Sugata is convinced that it’s related to an alleged ‘new continent’ that’s floating around the planet. According to Sugata’s calculations it’s set to pass above their town at midnight, and sends Tomoki to check it out. Little did Tomoki know that at that moment, a scantily-clad angel would fall from the sky! Calling herself a pet-class Angeloid named Ikaros, she promises to fulfill Tomoki’s every wish. Now, Tomoki is able to manipulate panties and do equally as perverted things with ease; but what is Ikaros really here for, and are her motives as pure as they seem?
Both series deal with mecha type story plots, both give a little bit of ecchi but in no Otoshimono the protagonist gets a run for his money with the girl from space and his next door neighbor. Sora no Otoshimono has a pretty good plot overall and is one to watch.
When deadly asteroids threaten Earth, an elite team of interceptors--the Meteor Sweepers--are formed. Now, rookie pilot Honjou Mikaze and her three friends are caught up in tumultuous events that may expose a sinister conspiracy and put the fate of the world into the hands of a few young girls...
Teenage girls, high tech weapons, save the world... Both of these anime have a lot in common. Stratos 4 has a little more realistic premise (aliens notwithstanding), shoot down meteor fragments to save the world.
Infinite stratos is a bit more science fictiony, with personal mechs, and what might as well be magic. Both start off fairly similar. Protaganists going to school, learning to operate the high tech equipment, deal with personal stuff, things like that.
IS is a little different in that there is a romance/harem thread to go along with it, Stratos 4 lacks both the Harem completely, and no real romance to speak of.
While different, if you like to see Teenage Girls (and a guy in IS) fly planes and mechs and save the world, if you like one, I highly recommend checking out the other.