Blue Gender, Godzilla 1: Kaijuu Wakusei Recommendations
Both anime are set in a post-apocalyptic setting with a similar vibe. They both focus on humans fighting for their lives against giant monsters and want to take back the Earth from the invasion. They are also both action-packed anime as well. If you like one, you may like the other.
These two anime focus on humans colonizing space after the Earth was wipe out by giant monsters. They both have humans trying to take back the Earth from other powerful monsters and have Mecha to use for combat against other giant monsters.