One of my favorite series, my top picks would probably be Red Alert 2 and Generals. I feel both have stood the test of time and are still a blast to play. The older ones of course have their great soundtracks and attitude of the videos.

I got C&C3 not too long ago and it was just ok. Cool to see the series a little modernized. But yeah, I heard 4 was an abomination. Red Alert 3's demo also turned me off.

I'm real sad EA decided to unequivocally commit the entire series to a Free to Play model, with no exceptions.