Ummm, like are you looking at the classic 4X game? Stellaris is more of a strategy game, resource management and they have added better combat this week. If that's what you are looking for, there are a ton of good ones out there, starting with Distant Worlds, Galactic Civilizations 3, Space Empires IV and V (although dated?, Sword of the Stars 1 and 2, Endless Space 1 and 2, Star Ruler 1 and 2 and MOO of course and Sins of a Solar Empire.
If you want more of an explore, fight, buy better ships, you know, space rogue stuff, there's Rebel Galaxy, Starpoint Gemini 2 and Starpoint Gemini Warlords, which mixes fleet work in there as well, as does Polaris Sector.
If you want a space simulator try Orbital, it's free and you'll get all the orbital mechanics you'll ever need.