Excellent games. With the exception of
C&C4 (BURN IT! BURN IT!) and debatably
Generals (Which, while a competent RTS on it's own, was a terrible C&C).
This is my personal list of the games from best to worst. (Assume any expansions are in the same position as the main game)[footnote] Oh, and this isn't counting Renegade, which you'll either think sucks balls or is fairly average with pretty fun multiplayer. [http://tvtropes.org/pmwiki/pmwiki.php/Main/YourMileageMayVary][/footnote]
Red Alert 2
Tiberian Sun
Red Alert
Command & Conquer (Original aka Tiberian Dawn)
Command & Conquer 3
Red Alert 3
-------------- [The C&C games actually worth buying line] --------------
Generals
Command & Conquer 4
That's just my personal opinion though. Some people thought
Generals was great, others (like me) didn't like that it lacked a lot of things that they felt made C&C what it was. I've heard various different opinions of where the series began to suck. Some say after
Tiberian Sun, some say between
Red Alert 2 and its expansion pack (
Yuri's Revenge) and some are even adamant that the only good C&C games are the original
Tiberian Dawn and
Red Alert.
As a whole though, I believe the
Command & Conquer series has provided some of the best specimens of the RTS genre we've had so far.