I grew up on the CnC games: Red Alert, RA2, Tiberian Sun, etc. My friend in middle school was a diehard -craft fan and we had long, spergy arguments about which series was better. I preferred CnC cause I liked the alternate-history/alternate-future angle of the whole series. Granted, the series has since turned to shit. RA3 was an embarrassment. I wasn't a fan of the "let's steal some cred from CoD" Generals either.
I played Civ for a while, but then found the EU games. I played the shit out of EU3, 4, and CK2. Some of my favorite games were when I played as Venice and controlled an empire from the Mediterranean to the south pacific and paid Austria to fight for me in Europe or when I played as Russia and broke up the HRE...but Paradox's DLC strategy is getting a little wearying. I stop playing the games for a couple of months only to return to find another 40$ of DLC is out. CK2, especially, is getting really uncomfortably bloated and I've heard that EU4 is nigh-unplayable if you don't have the Common Sense DLC.
I also really loved the Total War series before the remakes (Rome II, Shogun II) and the post-medieval ones (Empire/Napoleon).