If you liked the Girls und Panzer anime, the Anime-Planet community thinks you'd like:
In the year 2079 CE, malevolent creatures known as Worms arrived in our galaxy, wiping out mankind quickly and efficiently. Finally, when the war's outcome seemed to favor the invaders, humanity united and nuked its own planet in order to survive. Though the Worms were defeated, 50% of the Earth's land mass submerged under the ocean, and 90% of all young men were killed in battle. Now, several years later, the Worms have returned. The world's best hope for survival is the genius Karen, the swordswoman Otoha and quick-thinking Eika; together, they make up the Sonic Diver Unit, a mechanized unit capable of taking down the Worms! Yet the powers that be are skeptical of its force and aptitude. Can the girls prove their worth, and take down the enemy?
Cute girls doing military stuff that is highly age-inappropriate, all for fanservice's sake - that sums up Girls und Panzer and Sky Girls alike. I didn't really enjoy either, but they will appeal to the same audience.