Choices really, We all have games we like and there all from different genres, I know no one that only likes one type of game or series exclusively.
And on the subject, I thought C&C went sour right after Red Alert (with Generals being a somewhat brighter spot after it -- though not because of the campaign).
The mainline C&C series was fine (imo) until 4 when they decided to make changes for team based multiplayer (No base building, different classes, no resource collecting, etc)
Red Alert series. First was good, second one too -though it was corny. Red Alert 3 was painful, but not as bad as C&C4.
Generals I liked, though considering how some of its changes made their way into following games, I think it was a sort of test bed for ideas as well.