Oh God, Panty & Stocking With Garterbelt was good stuff: GAINAX anime with a distinctly American art style (Genndy Tartakovsky and Craig McCracken-esque, specifically). But then it would randomly jump into totally different styles particularly when the titular (heh-heh) characters powered up.
It was the Honey Badger of anime, and sat near the top of our first full season of reviews here at RABUJOI four years ago. Our only issue with the show is that it ended on a cliffhanger and, to our knowledge, a sequel that resolves things has yet to be announced. Which is a damn shame.
The OP was literally like ten seconds long, but the ED was a full minute, as shown here. The combination of serious but very catchy music (“Fallen Angel” by Aimee B) with colorful, cutesy portrayals of Panty and Stocking in horrible, potentially fatal situations was always a great way to end the craziness.