Right now I'm giving Cossacks 3 a go. The campaign is kinda annoying so I think I'll skip it and play some skirmish matches, after I'm done with those I'll give warrior kings a go, I remember playing that as a kid, though I also remember being annoyed by how slow it is; is there an in-built speed up option? If there isn't, I'll just speedhack it then.Hmpfh, difficult tastes. Your base-buiding focus does not allow for stuff like Battlezone or Myth.
Sci-fi.
Total Annihilation (plus its Fantasy cousin, TA: Kingdoms and its modern heir, Supreme Commander). Weird in scale. Base-building is essential (in SP TA base-pushing is a legit strategy). Kingdoms has issues, but the campaign tries to be more varied and the factions distinctive. Fuck the Iron Plague though.
Z: Steel Soldiers. Old-style, C&C style. I don't think it's up your alley though.
Perimeter. YOU LIKE BASE BUILDING WE HAVE TERRAFORMING BASE BUILDING AND BAD PERFORMANCE ALL IN A RUSSIAN RTS PACKAGE
Fantasy
Warrior Kings (and its weird exp pack, Warrior Kings Battles). Should be good. Good base-building options. Interesting economy. Different factions. Baseline campaign is nice and varied.
Dragon Throne: The Battle of the Red Cliffs. It's not fantasy, but it's Chinese so it's as good as fantasy for me. Weird mixture of different map set-ups and play styles. Try the demo, methinks you'll like it.
Hmmm. Paraworld was a valiant attempt, but again not what you are searching for.
I played total anihilation half a decade ago, I remember liking the concept, but I didn't play much of it, so I probably didn't like it (maybe I didn't like the controls? I don't remember).
I donno about that dragon throne game, I'll have to think about it. I played a demo to it when I was a kid, and I remember being very confused.
Ye, it's great, until you realise there's a defence tower cap, and now you can't finish your giant tower square of death...I love me some base building honestly, especially making a huge base full of walls and towers and whatever cool defenses one might make.