Dude! You gotta try hearts of iron! The whole series is good, but 3, 4 and 5 each have their own AI that predict your movements. (3 is kinda predictable, 4 is better and 5 is just straight up impressive.) The game focuses not just on strategy, but logistical warfare as the majority is spent focusing on supplying, developing and positioning your troops.
Also you can always try the Command & Conquer games if you think its too complicated. If you've never tried it, I'd start with Red Alert or Tiberian Sun. Its simple enough to use, complicated enough to give you a challenge and the music is awesome. Think open-world tower defense.