The best chair is no chair! So for me I use a low back mesh computer chair or a low back wood chair. Less is more as they say.
As a test get a basic stool and see if it sounds different compared to a one of those gigantic lazy boys chairs or IKEA POANG. You will be amazed at the sound quality.of your systems with less.
If you must go with something that is heavy leather padded...at least get something that will NOT cover your head/neck area.