I'm halfway through The Whisperer in the Darkness - BBC Radio4 podcast. It's very good if you like this sort of thing: "An investigation into witchcraft, the occult and secret government operations." And it's a quirky format - a podcast within a podcast. It's suspenseful but not overly dramatic like some podcasts can be.
Radio 2 has a lot of music documentaries. I haven’t listened to anything recently but a couple of years ago they had a great one on Andy Williams. I’ve also enjoyed listening to Johnny Walker’s Sunday Afternoon programme, The Sounds of the Seventies. Gary Davis does Sounds of the Eighties and Tony Blackburn does Sounds of the Sixties.
The High Low is amazing, but they're on a break atm. The Secret World of Slimming Clubs is really funny (especially if you've ever been to one), and I've also been enjoying the Broken: Jeffrey Epstein six-part podcast but not finished it yet. Conspiracy Theories is really good too.