Ginga Sengoku Gunyuuden Rai

both shows talk about people who fights each other to unify all the people and to achieve eternal peace; in both shows you cannot determine which one is the bad guy, because everyone has his own motivations and his own understanding of peace. 

South Asian themed Space Opera both scarred protagonist pilot a red Spaceship, and are strong in fighting  

Obviously both anime are of the rare space opera species. They are both not to easy to get into, Ginga Sengoku Gunyuuden Rai because of the bad English subtitles and Ginga Eiyuu Densetsu because of the old and unuasal art and seriousness. The narrative style is more or less the same. The battles are simular, with more interesting tactics in Ginga Eiyuu Densetsu. Both handle moral aspects of war, which are a lot deeper and more detailed in Ginga Eiyuu Densetsu. Both have some romance one the side. The worlds of the animes are in space but with a lot of historic elements, Ginga Sengoku Gunyuuden Rai with chinese elements and Ginga Eiyuu Densetsu with French Louis the XIV stuff. Ginga Sengoku Gunyuuden Rai sure is a nice space opera but Ginga Eiyuu Densetsu is epic. If you wan't to watch just one I would recommend Ginga Eiyuu Densetsu, also it takes much more time to watch it. But if you allready watched one and want something simular, make sure to give the other one a try. read more 

They are both good space opera anime that involves a lot of fighting in space for a certain goal. I would recommend both of these towards any sci-fi lover! 

Being of the same Sci-Fi genre of space opera they share some common elements like the growth of a young boy that becomes relevant in the story as he evolves and both are in an environment of war between space reigns with all the political issues and combat action of spaceships. Sekai no Monshou (aka. Crest of the Stars) takes a more personal aproach to the story and GSY Rai (aka. Thunderjet) takes a more action and great scale approach. Both great and dramatic stories with enough character development one more serious than the other. 

Both are Space Opera, focusing on tactics and political maters was it in defending ones Empire or Expanding it, thought Thunder Jet has a feudal Era theme while Tytania has a western theme.