PCGamer has put up a list of the top strategy games available for the PC. Both Galactic Civilizations II and Sins of a Solar Empire made their list!
Galactic Civilizations 2
Andy Kelly: If you’ve ever wanted to conquer space with an army of customisable doom-ships, this is the strategy game for you. It has smart, creative AI, and a full-size game can take weeks to complete.
Sins of a Solar Empire
Chris Thursten: Sins captures some of the scope of a 4X strategy game but makes it work within an RTS framework.
See the full list here: http://www.pcgamer.com/best-strategy-games-on-pc/