Soviet Heavy said:
Company of Heroes and Dawn of War spring to mind. Relic has a thing for making incredibly fun RTS games with insanely imbalanced multiplayer that still manages to be fair.
I wouldn't call necrons in DoW

C balanced or fair

But I still recommend dawn of war and its expansions, the single player is a ton of fun.
Age of empires series. While from a nostalgia standpoint people prefer 2, I'm gonna go ahead and say mythology is better. Cooler factions, a good expansion (Atlanteans are a bit op, not too bad) and more badass units. AoE 3 is good, just not my thing. Unlike all the others, it's set during colonial times, so a
big departure from the series. Having played all the others for as long as I can remember, it threw me off a bit. Someone new might find it awesome though.
EDIT: Oh, for turnbased strategies, the fire emblem series kick ass. I'd say my favourite is path of radiance for gamecube. If you've got a Wii or a gamecube, try and get that. Then there's a bunch of older ones, the two easiest ones to get now are probably shadow dragon for the DS (Pretty good, but there are better ones) and Radiant dawn for the Wii, which I'm not a fan of, I played a bit, never got interested.