Dest for a serious response I'll tell you I've been lucky enough to use several - notably the HM Aeron and Embody, as well as Steelcase Leap V2 since work pays for them.
Out of those three, for me, it goes:
Leap V2 > Embody >>>>> Aeron.
My friend who literally is a sales rep for high end office equipment told me that for every 3 Aeron he sells, 2 are returned and exchanged for something else. A lot of people apparently complain about the hard plastic frame at the front of the chair (where the back of your knees would rest). I didn't really have this complaint but regardless I wasn't impressed with mine. My friend claims that Aerons work better for "huskier" peeps, despite the three different sizes available.
I now have a Leap V2 and love it.
Definitely try all them out though, maybe you'll enjoy one over the others. And all can be found for around 400 used, except maybe the Embody, may have to add on 200 or so.
He also says the HumanScale Freedom are great but extremely hard to find used.