I used to listen to a lot of them while working. I'm down to 3 now.
The Pinball Podcast - I miss Don, but still enjoy the show. Opening bit of "what they have been doing in pinball lately" goes on a bit too long for me. But I listen to every episode.
K Pinball Podcast - Short and to the point. My favorite for getting any news or rumors. But his comedy bits almost always fall flat for me. Also when there is no real pin news he resorts to basically reading Pinside. Listen to just about every episode anyway.
SDTM - My favorite for the review of a new pin. Love those episodes. Only listen based on topic though.