Soooo many great arrests....but I think the one I take the most pleasure in watching again and again is Dale Kingston in "Suitable for Framing." He was so cocky, so condescending, just such a bad, bad person. He's ready to send his sweet Aunt Edna to jail for life so he can get his hands on his dad's priceless art collection.
The very end, when an exasperated Kingston questions Columbo, "You..touched..them?" Claims it was a trap, that he set him up just then and in one of the best closing scenes of all time, out come Columbo's hands from his pockets in latex gloves.