My favorite would have to be "Down Range Radio" with Michael Bane. Only problem with the show is that for some reason, he feels the need to play three (3) full-length songs throughout the show, often from really "out there" groups. I just fast forward over the songs. He is a fantastic commentator, very humorous and energetic while being also being humble and honest. Ads are kept to a minimum, and he just has a lot of great things to say and it's just plain entertaining. He hasn't made a show for a while though.
I also really like "Gun Guy Radio", firearms talk without the politics (their slogan). They have one main topic per show and go really in depth. I've learned more about guns from that podcast than any of the others.
I honestly have to say... and I'm sure many will get mad at me for saying this... but while I do in fact listen to Tom Gresham's "Gun Talk", it's my least favorite. I like Gresham and he does amazing things for the firearm's community, but I've found the show to be repetitive and heavily laden with advertisements. They have a ton of commercials, and more than half of their guests are just people pushing their product. Tom can also be somewhat arrogant at times, I've caught him cutting people off only to deliver a wrong fact as a counterpoint etc. etc. I also don't like the "after show", they play it up as edgy but it's really not and I can't stand the gal's voice who is on the after show.
Those are the main three I listen to "on the regular" as it were.