*has a massive seizure*
I can't believe no one recommended the Tenchi Muyo! Ryo-ohki OVA. It is my favourite anime. Goes to show all of you have bad tastes.

Not only are the character designs excellent, but each episode is executed fantastically. And the humor and jokes? They timed and delivered brilliantly. I can't tell how many times I've nearly killed myself laughing.
the onsen scene in ep. 4. Washu nurse scene in ep. 7. heck, the whole of ep. 7. A lot of people say there is no plot in the series, but there is. If you pay attention carefully and/or watch it multiple time, you will realise there is a deep and complex plot (and that's accounting the books too which go into even more detail, also by creater Kajishima-san.)
Oh ya, Kajishima-san and AIC; hurry up and get ep. 17 (OVA3 ep. 4) out. The suspense is killing me.