Well, it would depend on your interests. I'm into astrophysics, so I listen to Astronomy Cast (hosted by Fraiser Cain and Dr Pamela Gay, this one is probably my favourite), Ask a Spaceman! (hosted by Paul M. Sutter), StarTalk (with Neil deGrasse Tyson and Chuck Nice, often there's other presenters too), the Supermassive Podcast (by the Royal Astronomical Society), and the NASA ones too (like Curious Universe and Houston We Have a Podcast)

If you're not as into space stuff, I know the Lateral and the Technical Difficulties are great if you want more nerdy stuff from Tom Scott and co. There are plenty of awesome ones out there (as long as you avoid the sketchy political commentary, manosphere, or similarly awful sort)