I had an Aeron at my previous job. My experience with that chair was that it tended to act like sandpaper for whatever I had in my back pockets, even a very thin wallet. I bought a Leap for my home office and I really like it. In my opinion, the upholstered bottom and back on the Leap are more comfortable than the mesh on the Aeron. YMMV.

No matter what chair you're in, if you are going to be sitting all day - get everything out of your back pockets! Otherwise you're putting strain on your lower back, and it might punish you someday.

I bought an Aeron over ten years ago and have never regretted it. Everyone's different, so go try chairs and make sure you have a return period. What feels fine after five minutes in the store may not feel so good after five hours of coding.