Much as I love All Killa No Filla it is practically 90% filler! I don't actually learn much about serial killers from it which can be unbelievably frustrating at times so I just go off and google the killers instead. I realise that makes me sound weird. 
They walk among us is very thorough and often about cases that aren't overly well known. The narrator's voice is an acquired taste , however.
99% invisible is a podcast about design and architecture but it's a bit more tangential than that. Has covered fascinating subjects in the past.
Evil Genius with Russell Kane where comedians discuss if a popular ( usually dead) figure was Evil or a Genius
An hour or so with Sue Perkins - lovely chat.
Do the right thing - silly panel game
Something rhymes with purple - Susie Dent and Gyles Brandreth talk about language.
The Guardian Today in Focus podcast covers topical news issues in more depth
Distraction Pieces with Scroobius Pip - more left field guests but fascinating chat.
Plus yes to Athletico Mince, Off Menu and RHLSTP!