These are good, maybe similar, and have high frequency of very interesting episodes:

  - People I mostly Admire (Steven Levitt/Freakonomics Radio)
  - The joy of X (Steven Strogatz, discontinued)

Both are in the style that the host talks with an interesting guest about their work. Coincidence has it that in the most recent episode of PIMA, the guest is the host of the other one, Steven Strogatz. They normally don't collaborate but have their similarities.