They're easy-going, likeable and extremely knowledgable with a real desire to inspire interest in the hobby. The GROGNARD files has featured on their pod, but it doesn't invalidate my nomination as many will have also gained their selfless promotion of the projects that they admire: from indy games to mainstream, from dyed-in-the-wool gamers to those discovering the hobby for the first time; they have an interest in it all.
I like many podcasts, but this is the one I enjoy for its insight and entertainment.
The Rolistes Podcast. https://rolistespod.com/
Kalum goes out of his way to bring news from the rpg world by going to conventions, interviewing players, game designers, game publishers, gaming clubs etc... He's always keen to hear and investigate what others are playing in other countries. Also this year he had the funniest actual play recordings. Check out the lone wolf one for a good laugh.
I'd like to nominate the Roll For Combat podcast (http://rollforcombat.com/). A great actual play podcast with GM/Player tips, with a good, experienced cast of players. And Paizo developers jump in for interviews and or playing NPCs. RFC also supports a great Discord channel/community of players.
The Play Better Podcast has some of the best actual RPG play out there, and there regular podcasts are very informative about new games coming out. http://playbetter.libsyn.com/. Give it a listen if you haven’t discovered it yet.