A second vote here for The Adventure Zone, which is enormous fun. I've been doing a lot of driving lately and it's sustained me well. It's best to start at the beginning, though, and I'm now just over a year behind! There are more than 50 hour-long episodes.
I also really like War Rocket Ajax, a comics podcast which has even featured Arthur Wyatt at least twice. Their ranking projects (one for characters and another for stories) are kind of fascinating.
Also the Thrill Cast, of course. I listen on looooong drives, and I now associate Molcher's voice with the need to urinate.