I'll give three:
"Philosophize This" by Stephen West is a quite good and accessible series on philosophy. It's largely worked through the historical overview and several of the recent segments have been on (reasonably) modern and unfamiliar (to me) topics, with the "Ethics of Care" episode this post August being standout excellent.
https://www.philosophizethis.org/>
Ethics of Care episode: https://www.philosophizethis.org/podcast/episode-158-the-cre...>
My notes on EoC: https://diaspora.glasswings.com/posts/60cf1410e72f013a68ef44...>
Peter Adamson's "History of Philosophy Without Any Gaps" is now well into its third decade, 400th episode (in the mainstream podcast), and the 16th century (Jean Bodin). I rank it after West's effort only because I feel West can use the advocacy more. Both podcasts are excellent, Adamson is well supported through a tenured faculty position and institutional funding. Older philosophy provides insights into the development, and history of ideas, including (many, many, many, many) false starts and wild-goose chases, but also often startlingly modern thinking in ancient times. Having caught up with the full back-catalogue, I've returned to the beginning for a second listen.
https://historyofphilosophy.net/>
A third excellent series is "Complexity" from the Santa Fe Institute, largely looking at systems and complexity research. Topics, production, and editing are excellent, and definitely definitely definitely check out the show notes for additional references.
Actually, that last goes for all three of these podcasts, which really put the additional effort into documenting what was discussed.
Complexity: https://www.santafe.edu/culture/podcasts#Complexity>
All of the above are commercial-free (West does solicit Patreon support at the beginning of each episode, Complexity notes SFI goings-on, both are brief and appropriate), which I find makes a huge difference for me in how approach and rate podcasts. There are any number of podcasts which include commercial spots which I have to steel myself to listen to.
I'll throw in a "fourth" as a cheat: the New Books Network, which is not a single podcast but literally a collection of well over a hundred channels on academic topics (though many individual episodes will appear on multiple channels). This is the project of Marshall Poe.
Quality is uneven, both in production and hosting, and there is advertising, often sudden and intrusive. Still, as a place to find academic work and deep dives into topics very often not dominating news cycles or other cultural coverage, and for the huge back-catalogue (dating to the mid-aughts), again, an excellent resource. Some hosts are excellent, others ... grating with time. But I find myself returning frequently and being well rewarded more often than not.
https://newbooksnetwork.com/>
There are a number of other academic and book-related podcasts, including from the London School of Economics, Yale Press, Intelligence Squared (both UK and US), and more which I can't help but mention, though the four pods listed above deserve top billing. I'm also increasingly listening to a number of foreign-language / foreign-service podcasts, in a number of languages, which I'm finding useful as a learning tool.
Readers may note that none of these podcasts feature current or technical topics. I consider both aspects strong positives, as overexposure to both news and tech has been a constant. Deep dives into specialised topics outside the mainstream is useful for surfacing new (and old) ideas and associations.
I have well over 100 subscriptions, which I dip into as informational, entertainment, and relaxation resources. I've listened to nearly 2,500 hours of podcasts so far in 2022, including several not listed above.