Depends what you want, really. Here's some of the stuff I've enjoyed.
Over the top silly action - Kill la Kill, Durarara!
Mushy emotional drama - Kokoro Connect, Anohana: The Flower We Saw That Day, Ano Natsu de Natteru, Blue Spring Ride, Toradora!, Tari Tari, Hanasaku Iroha
Charming and lighthearted - Non Bon Biyori, Usagi Drop
Comedy - Monthly Girls' Nozaki-Kun, Tonari no Seki-kun: Master of Killing Time
Bit of everything - Angel Beats
EDIT: I forgot to mention that Crunchyroll often doesn't have the OVA episodes, extra episodes usually on the DVD and BluRay versions. Sometimes it's just icing on the cake, but for something like Kokoro Connect you'll really want to track down those episodes elsewhere.