Well, I guess I could shop online retailers, but in physical bookstores the first volumes are basically no longer carried.
A lot of things have abbreviated titles at this point. Did you stop in season 1, the OVAs or season 2? I delayed starting season 2 when I realized there were probably OVAs that would explain why it felt like I was missing some critical plot details.
IDK. Anime-wise, probably Kokoro Connect (I like stuff with strong slice of life elements, but this one has some serious drama to it since the drama ties into a subtle yet central to the plot supernatural element). Or Genshiken. Or the various Negima! OVAs that are basically the more actiony parts of the manga animated.
As for manga series, Ken Akamatsu's trifecta of romcoms (Love Hina, A.I. Love You, and Negima!) top the list, followed by Genshiken and Chobits.
You can basically glean my all time top ten from the faves section and the about me section of my MAL profile:
http://myanimelist.net/profile/donavannj