Soukyuu no Fafner: Dead Aggressor - Right of Left

Both of them show a desperate struggle against a foreign enemy using mecha that can either be a blessing or a curse. The Strains are only good if you have a mimic for them while the Fafner's slowly eat away at the pilot. Both have a major dramatic climax that leads to the resolution. 

Bokurano and Fafner-Right of Left are mecha titles in which the robots serve to develop the characters. In both series children are forced to wage an excruciating battle with an aura of bittersweet tragedy that weights upon everyone. Bokurano does an exceptional job in fleshing out a rather vast cast while Right of Left focuses more exclusively on two characters; in both the human element is much more important than the action and these somewhat underrated titles deserve considerably more attention than they receive.  

Saikano and Fafner-Right of Left share the same mood of deep tragedy that accompanies the involvement of children in a ruthless conflict. In both, technological advancements are made to help with the war effort and these same backfire and cause considerable damage on the child fighters. A very moving romance develops in both titles. Saikano, however, is exceedingly sad while Left of Right is more bittersweet.  

Fafner-Right of Left and Neon Genesis Evangelion offer a very character driven approach to the mecha genre. In both cases it is the human conflict of children who must fight that takes the spotlight. With this said, Right of Left is considerably more conventional in its heart wrenching tale while Evangelion eventually becomes a highly complex exercise in deconstruction and emotional dysfunction.