Ginga Eiyuu Densetsu, Arslan Senki Recommendations
Based on novels of Yoshiki Tanaka, they are both epic tales with charismatic and eyecandy protagonists, exceptional scriptwriting and dialogues, philosophy, politics, war, and strong supporting characters
Sadly, while the whole of Lotgh was somehow miraculously adapted into a long runing OVA series without being canceled, Arslan's anime covers only a portion of the source material and leaves things dangling in the middle.
Both are by the same author, although one is a medieval world with light fantasy and one is a space opera setting. While Legend of the Galactic Heroes follows tactics and political situations more closely, the Arslan OVA follows Arslan's group as it becomes an army. Both portray each side of the war going on in grey shades, although Arslan shows the opposing side in more of a negative light and is a bit simpler in terms of morality.