I have an Aeron. I'd trade it in a heartbeat for a Humanscale Freedom chair. The Aeron is not bad, just like the aesthetics of the humanscale, but really haven't sat in one. We used to have a few humanscale chairs at the office though, pretty nice stuff.
I hve an Aeron at work; it is comfortable enough. At home, I have a Steelcase Leap, which I think looks nicer than the Herman Miller. The pellicle "fabric" mesh on the Herman Miller is abrasive and can wear holes in your clothing all the while keeping you cool. At home, I also have an Eames Aluminum Group Soft Pad Lounger and ottoman, which for style looks much nicer than either of my task chairs.
I have an Aeron at home and at work and find it very comfortable. Whatever you get, make sure it is thermo-neutral (made of an open fabric like the aeron). Padded chairs will feel comfortable at first, but quickly make you warm. Herman Miller has a whitepaper on their website about this issue.
Just bought a Haworth "Zody" chair to replace my home office desk chair. While not inexpensive (I paid $600 for one that was used for about 30 days - they retail for >$800 loaded), they are not ridiculous. It has adjustments and great lumbar support. Pretty pleased after my first 6 hours in it completing a big presentation.