Well the Aeron is considered to a design classic and one of the finest desk chairs of all time whereas HM describe the Embody as their new flagship.
Unless you go and try one for yourself, all you will on the internet are opinions from people with different body sizes, shapes, posture, desks, habits and preferences.
I was lucky enough to work in offices for 17 years where everyone had an Aeron. Chairs were never a topic of discussion, that's how good they are. Only a tiny few ever developed faults and nearly everything on these chairs is replaceable.
When I changed companies and started WFH, I bought my own top-of-the range Aeron and love it, although with hindsight I should perhaps have gone for the [edit] C size instead of B but it's fine.
As was said last March, if you can but on sales or return I guess you have nothing to lose but it would be prefereable to try one out at a store first.
Oh and when the HM guy delivered my chair, he didn't just hand over the box but actually spent time to advise me on how to set the chair up for the correct posture. Class.