Best Space Strategy Game?

FTL ofc

Sins of A Solar Empire.

Got go with what several have stated, Sins of a Solar Empire.

Try AI War.

Hmmm... If grand strategy or 4x is your thing I'd go with the majority here and check out Master Of Orion 2 in the two-pack available on GOG.com (It's probably on sale right now, but it's dirt cheap on GOG anyway...) Whatever you do, DON'T go near Master Of Orion 3, unless you like intensely overwhelming, complicated games. I would say to try it if you're already a bit of a veteran at these games...
Endless Space was very good from this year, but I feel that Galactic Civilizations II: Ultimate Edition is the more appealing option in both accessibility and price.

Not sure if this one counts, but noticed the other day this was updated on GOG:

Sid Meier's Alpha Centauri.

The true sequel to Civilization 2, set on Alpha Centauri. Has a surprisingly detailed and well told story-line for a big-ass strategy game and GOG just updated for no extra charge adding the expansion pack Alien Crossfire which adds a tonne of new features, story and factions to play as.

FTL

this thread is awesome, i played hegemonia, galatic civilizations and homeworld quite a few years back. Now i'm looking at new games like these. i'm going to probably try every game mentioned here. thank you OP!

Don't you fucking dare suggest there's a "best"....

So many good games...

X3 Terran Conflict is a very good game.... huge learning curve that can be frustrating, but it's worth the effort.
But it is the best Space Game out right now. I just installed the X-Tended Mod for X3TC, which is about 800-900Mb in size and improves the game alot. Played for 24+ hours in past 4 days....haha

here's an old trailer, but still looks good.

https://www.youtube.com/watch?v=UAQ7x8K6Yjg

Imperium Galactica 2. An old game, but a real classic. I think it was recently re-released on iOS.

Master of Orion 2.
Nothing comes even close to it (which is very sad).

i dont know this genre but why eve is not here?

Endless Space, the UI and the dev are awesome, they keep releasing new content for free :D

X universe ( X2: The Threat, X3: Reunion + exp)

Dark Colony and Warhammer 40k

Star Ruler

Or if you want to go Hardcore head in space games, EVE Online ;)

Nexus: The Jupiter Incident.

Star Wars : Empire at War gold pack. Its space and land combat. Old but I enjoyed it pretty much.

Clicky

Not space strategy but go check ou Star Citizen, looks damn awesome.

FTL is great space kinda strategy.

The best is hard to choose, but I have to say... Sins of the Solar Empire: Rebellion. Really good one.

Space rangers