Ground Control is does not feature the base-building of WC/SC, but are excellent RTS mission-based games.
Homeworld: Deserts of Kharak is another excellent one.
Earth 2150 includes the base-building, as well as a very cool "persistent homebase" mechanic for the singleplayer campaigns, where you build bases in the mission sites but also have a home base that you can transport units to/from, for use in future missions.