I'll still say Avengers.I thought the Cap-Skrull storyline went on too long,but I enjoyed the whole series.
Young Justice was great,but there was just too much crammed in.The Light/The Reach,The Junior SuperFriends,Characters that dropped in and out without any sense of their importance,Characters like Wally getting the shaft,while Blue Beetle gets center stage,Etc.I mean,I like a complex story,but I felt I needed a score card to keep up with all the plots.
I'll admit though,When YJ was good,it was freakin' awesome,and I will miss it.But I don't think I have the emotional attachment that many others have for it.