In a possible future, mysterious devices called plates create robotic "Antibodys": Brain Powerds, or Grand Chers. In this world, a monumental structure known as Orphan lies at the bottom of the sea, slowly making its way to the surface to fly into space; however, its success would result in the death of every living being on the planet. Already, natural disasters are prevalent due to its ascension. In order to stop Orphen from obliterating humanity, the organization known as Novis Novah uses Brain Powerds to battle it, while Orphan searches for more plates and defends itself using Grand Chers. In the middle of this war is Hime, a girl who found and mastered a Brain Powerd on her own and joined Novis Noah, and Yuu, a boy who has served Orphan all his life but now decides to escape and fight alongside Hime. Can these two young people make a difference in this war? And what is the true purpose of Orphan?
In the future, a devastating event known as Second Impact destroyed Tokyo as we know it, giving rise to the current day Tokyo III, a city under siege by mysterious lifeforms known only as Angels. Mankind's only defense are Evangelions, man-made machines piloted by Rei, Shinji, and Asuka, all who are the tender age of fourteen. The fate of Japan and the entire world now lie with these children, though they might not have the power to save the most important thing of all: each other.
Both these series deal with human pilots and their interaction with their robots, plus the complexities of human nature.
Both series contain alien fighting machines (Antibodys in Brain Powerd, Angels in Neon Genesis Evangelion) that pose a threat to the world and opposed by a small organization that uses young individuals to pilot powered suits. Both series focus not only on the fighting of mecha, but also on the emotions and psychological condition of the pilots. If you enjoyed one series, you will probably enjoy the other.
Far, far away in a distant time, there is a tribe of people called the Golden Tribe who have the ability to create stars and foretell the future. They gave out a warning to those who have yet to mature: 'Move.'. Three tribes answered their call: the Silver Tribe, the Bronze Tribe, and the Heroic Tribe. Soon after, the Golden Tribe encountered a crashed ship in which only a baby human known as Age survived; they named the child's race the Iron Tribe and assigned one of the few living members of the Heroic Tribe to protect him and his race. Now, in a distant part of the galaxy, humanity is threatened with extinction at the hands of the other tribes. With only a prophecy to go on, they set out to the deepest depths of space to find their savior named Age -- humanity's last hope.
I'm not quite certain why exactly you would like Brain Powerd if you enjoyed Heroic Age and vice versa. Maybe it has to do with the fact that feelings and relationships are a big part of both series as opposed to lots of fighting (though there is plenty of that too) or the fact that the mecha are more organic and their pilots have a more personal relationship with them (though in Heroic Age the pilots and their mechs are almost indestinguishable). Regardless, I think both of these series are similar on several levels and if you enjoyed one, I think you will enjoy the other.