 If you liked
Koukyoushihen Eureka Seven
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 ...then you might like
Kidou Senshi Gundam Unicorn
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Both feature a protagonist with family issues using their overpowered mecha to protect an enigmatic girl who falls out of the sky, getting involved in a war they didn't want and enduring out of the power of love.
Both also explore the reality of throwing children into a battle, and are heavily based around the themes of belonging and family.
Think of Gundam Unicorn as Eureka Seven with better animation, a more directed plot and without the mind-screws.