Radiolab is, hands down, the best of all the podcasts. This seems universally recognized: I’ve yet to meet anyone who disagrees.

FWIW, I disagree (though I agree that everyone else seems to love it). It has high production values but I think it's pretty bad if you're actually interested in learning about something. They drag out even the most basic fact by coating it in (to me) extremely boring narrative, and leave out anything that would let you actually reason about the subject they're talking about.

I seem to be alone in this opinion.

I think Econtalk is a much better podcast for actually learning about something. Hardcore History also seems to be pretty good for this, though I've only just started listening to it.