Got a refurbished steelcase leap V2 from Crandall after my budget office chair shit the bed. been really enjoying it. My ass and back are very comfortable.
I work as, amongst other things, an ergonomist and was here to comment exactly this. The Steelcase Leap or Gesture are nearly always my recommendations.
I've been sitting in the same Steelcase Leap V2 for 8 years at work and it is still comfortable. I love it. When my current chair at home dies (it's good, but not "Steelcase" good) I'm biting the bullet and getting the Leap V2 at home as well.