Radio 4 and 6 here.
Whichever one I was listening to last tends to stay on until it annoys me, then I switch to t'other. You and Yours, Moneybox, Any Answers, Tom Robinson, etc.
Radio 6 I think caters for those of us who used to read the NME and listed to John Peel. Jarvis Cocker and Craig Charles are both excellent at introducing me to new (and sometimes very old) stuff, and when I was cooking the Christmas dinner a couple of years ago I had an education in good reggae. Informed, educated and entertained I was.