Brain Powerd

Sentient mechs, symbiotic relationships, homeships, little children onboard, somewhat balanced male/female protagonists... Plus they both have the war element, romance and something of a mystic nature inhabiting their planet. 

Alien invaders filled the earth. The setting of humanity getting decimated by aliens, losing horribly, being forced to draft kids, and the resulting mecha battles against said aliens are quite similar in style and mood.  

Tomino brain rot double pack. If you've already seen Brain Powerd you will easily make it through Garzey's Wing. Watch subbed for very poorly made but interesting concept-wise story, watch dubbed if you want to have a heart attack from laughing incessantly.  

One more Evangelion-influenced show depicting teens, religious imagery and incoherent story-telling. 

Both are made by "Happy" Tomino, and have similar plots, characters and robots (Even on the way they fight!). 

Two organisazions fight each other with mechas extraterrestrials 

In both the Main characters has relationship with the living mecha. 

When watching Brain Powerd, i couldn't help but think about another Tomino series, Turn A Gundam. Both shows have a lot in common, plus they both share some of the same voice actors, and a score by Yoko Kanno.