Pre-COIE:
All-Star Squadron
LSH
Teen Titans
BATO
Justice League of America (yes, even the Detroit years)
Infinity Inc
DC Comics Present
Post-COIE
Outsiders
LSH
Titans
Superman, Adventures of Superman and Action Comics
Wonder Woman
Infinity Inc
Justice League / JLI
Suicide Squad
Captain Atom
Doom Patrol (yes, I loved the Kupperberg DP, and the begging of the Morrison one, though I lost intrest after it went Mature Readers)
Probably forgot some, and will kick myself later for that, but I think those were my favorites.
Peace
I wasn't really a DC person, but these titles overcame my Marvel bias:
The New Teen Titans
The Legion of Super Heroes
Firestorm The Nuclear Man
Justice League