I've been a huge fan of Hardcore History with Dan Carlin for years. He's become the standard by which I judge all other podcasts. Detailed and intensively researched epics on ancient (and modern) history. Preet Bharara is a fantastic listen too. Expert commentary on the political times from the US Attorney from the southern district of New York - fired by Trump for not returning an unprofessional phone call. The Pope's Long Con is a fantastic bit too. Really deep investigative journalism published right around the time of Rep. Dan Johnson's death. Dive into some weird Kentucky political lore and the fascinatingly and pathologically bizarre history of the "The Pope".
Hardcore History would have to be the objectively best podcast I've listened to. For those that haven't listened to it, I strongly recommend going the multi-part series called Blueprint for Armageddon. It's a 6 part series (all 2-3 hours long) focusing on the WWII, from the lead-up to the end of the war. Dan Carlin does an excellent job of providing what seems almost like a personal face to many of the stories.