Heya Ryan,
I'm a pretty big fan of the Command and Conquer series. I'm sure many will agree with me. Their most current release is Command and Conquer Tiberium Wars and they have an expansion pack out for it as well. I also like the previous release in the series. Command and Conquer Generals.
Generals is present day warfare, and Tiberium Wars is futuristic/Sci-Fi. Keep in mind that Tiberium Wars requires a pretty beefy computer to run it.
You can check out more info on them at IGN.com. IGN is a great review website with lots of screenshots/movies and good game reviews.
Those are both pretty awesome games
