In your opinion, what is the best real-time strategy game?

The only problem with Emperor for me is the boring campaign; they couldn't make it like in Science. At first, it seems promising, but then it just fades away.
And as for the second one, I've played it enough on Sega, and it feels like a wooden leg instead of a whole, healthy foot. Although, it's worth noting that I generally dislike consoles – both modern and old ones.