Vnlr: Come to think of it, and since people are recommending Sins of a solar empire left and right, you might also want to try out the Star Ruler games. 2 is here on GOG and is magnificent. You can find boxed copies of star ruler 1, but I don't know wether they come with mandatory steam or without (I have the regular steam version from my pre-gog days).
They are fantastic games. 1 somehow reminded me a bit of Supreme commander in space, rather than a fully fledged 4x rts, but star ruler 2 is quite another beastie in that regard. I believe there are demo's for both :)
Star ruler one and star ruler 2 (rather long videos, just skip through them a bit)
While I think that sins of a solar empire is a good game, it just never managed to captivate me somehow ... but it's well worth a try.
Tarm: Dude you're not being a bastard. The Kohan games ARE the best RTS games ever only rivaled by Sins of a Solar Empire. For me at least. :)
I agree on Rise of Legends. A very undervalued game that unjustifiable got crap because it wasn't what the Rise of Nations die hard fans wanted. It's a great game in its own right.
Vnlr: Nice to see a likeminded person :)
Also, if you can find them somewhere, the Myth games ... so much ...
I was about to mention the Myth series, Soulbringer being my favorite. However; I digress as they are not on GOG at this time. If you can find the Myth series and get it to run correctly they are pure joy with some frustration mixed in o_____O.