C&C is WAY too easy, doesn't require much strategy at all. If you build a big enough army you can always take out the other side brute force, and usually far under their suggested time.
Now C&C original is classic, and I give the makers a lot of credit for that one, since they basically started the RTS thing, and they C&C is what first got me into RTS, but the C&C games have gone downhill, and SC is an awesome game.