I've owned an Aeron, Steelcase Leap (v2), and the Embody. All for multiple years. I prefer the Embody. I can sit comfortably in it the longest without any complaints. I think it's almost the perfect chair.

The Aeron I found extremely uncomfortable, I could never get settled in it. I don't know why, but it felt just wrong (I had the correct size and it was fully loaded with all the configuration options and posture fit). I loved the Leap and only got the Embody because I bought all new office equipment and after sitting in the Embody a while I fell in love with it. Only recently (finally) got rid of the Leap and Aeron.

I can't give any reasons other than it feels the most comfortable and I can easily sit in it longer without issues.