If you just have finished Terra E and are looking for similar series in climate of old, good SF you 'd love Banner of the Stars. Both series in a scenery of unknown galaxy tryes to answer the most important question: what is the definition of being man, how far we can go improving our race, what if we are not alone in a space, what can we sacrifice for those who we love?
Large scale space battles and a focus on building an epic science fiction world are shared points. There is plenty of exposition and calm discussion of tactics. You will also experience the outdated, yet fitting and sometimes beautiful animation style. Finally, both shows challenge the view that democracies are the superior form of government.
Note that Seikai no Senki is considerably smaller in episode and character count. It is the sequel to Seikei no Monshou. While a great anime itself, watching Seikei no Monshou first is not strictly needed.
Both shows deal primarily not with action, but on character interaction and the political and social structures of the worlds they contain. Banner of the Stars is to Sci-fi as Good Witch is to fantasy.