I haven't tried the embody, but I am not a huge fan of the Mirra and Aeron. I think they are both decent chairs, but not worth the money (we have both at work, I use the Aeron).
I tried the humanscale freedom, liberty and world chairs and I was not a fan of the freedom at all. I am sure some people will love it, but I felt like the way it moves when you recline gives you the feeling of never being at rest. Might be the perfect chair for some people, but definitely try before you buy with that one. The Liberty and World chairs both felt pretty good and are reasonably priced imo, I just wanted something more so I kept looking.
I ended up deciding between the Allsteel Acuity, Steelcase Leap and Teknion Contessa. I bought the Contessa because I read good reviews (http://www.ergo247.com/teknion-contessa-review/
was the one that was most influential because there are quite a few good chair reviews on there). I haven't tried it yet (comes on Monday) but I can provide feedback then if it interests anyone. If it doesn't work out I will probably return it and get the Steelcase Leap.
Edit: Got my Teknion Contessa on Monday and I am a huge fan. I think it is really comfortable and looks outstanding. The pros for me are that the seat is definitely superior to the mesh seat I have on the Aeron I use at work and the recline feels natural. The cons are that the arms are not as adjustable as I would want, but on the upside they aren't as wobbly as some other chairs. I might take some pictures and make a short review sometime this weekend.Edited by LilBuckz - 9/20/13 at 12:30pm