Never really had the time or patience to listen to many podcasts but the few I have managed to sit through have been very good.
Serial and ShitTown are just phenomenal. Everyone should listen to them.
Other ones I like:
Lore: each episode is an explanation of specific pieces of folklore and and an examination of the existence or not. Ghosts, Gremlins, Elves, Vampires etc. My absolute favourites though were the studies of Springheel Jack and the Jersey Devil.
True Crime All The Time: exploration of serial killers. Fascinating.
The Prancing Pony Podcast: deep dives into Tolkien lore. I have listened to 250 hours of this.