Starcraft is more focused on base building like the original dawn of war. It's a more difficult and complex game. I'm not really sure what you like most in DoW.

Oh, it's got a pretty good campaign, the game is cheap right now too. The campaign might be impossibly difficult if you're not use to the more micro/macro intensive rts without cheat codes.

You could give more information. What are you looking for in you're single player experience? Starcraft is the best rts in terms of multiplayer, I can't say it has the best singleplayer since I haven't played that many rts games.