I've been using a Haworth Zody for 7 years, and I like it pretty well.
Nothing wrong with the Aeron, but I find the Zody is (1) a better price ($200 used for mine, or $650 new[1]), (2) more attractive, and (3) the adjustment mechanisms are smoother (armrests in particular).
The Zody has pretty much all the same kind of ergonomic options as the Aeron. Although, the backstop and forward tilt option is not standard on all Zody chairs for all time (mine has neither)