I loved the Aeron I used to have, until I hurt my shoulder swimming and discovered that its skeleton actually digs uncomfortably against the shoulder. That jarred me out of complacency about the chair's possible flaws, at least compared to others.
Haven't tried the Gesture but did have the Leaps somewhere I previously worked. I think a lot comes down to your feelings around breathability and feel of seat and back material. Personally, I like the mesh of the Aeron but there are a lot of people who prefer a more "traditional" chair material.
I loved the Aeron I used to have, until I hurt my shoulder swimming and discovered that its skeleton actually digs uncomfortably against the shoulder. That jarred me out of complacency about the chair's possible flaws, at least compared to others.