What are important features in a listening chair

Eames Lounge and Ottoman is my choice.
We have a pair of clones (widely available on Amazon in many grades of leather) in the music listening room (also good for reading and sharing coffee in the morning). We have three total, and they are great for the price. Authentic Eames loungers are still manufactured (by the original manufacturer licensed to produce by Eames). They are much better, but cost $5k+ depending on wood selection and leather choice.

I have an antique wicker chair with a comfortable cotton cushion and a small pillow for lower back support. Absolutely perfect for me.

My mother works for Knoll so I am lucky enough to have both a Barcelona chair as well as a Womb chair. I prefer the Womb because of the way the fabric catches the reflections around my head. The Barcelona is no slouch either, but nothing beats the comfort that the Womb offers.

I would say that comfort would be THE most important aspect for a chair you plan on spending hours in. Also consider the way the fabric interacts with the imaging and reflections. 

I sit on the floor.
Thats how I have been listening since 1958 when my dad used to play them old 78s. I am 71 now, still sitting on the floor.

gtechaudio60 nailed it. At least in the budget category. I had a very similar version of this. Light weight. Space-efficient. Supremely comfortable. Not only comfortable, but supports my head just about perfectly without coming up behind the ears. Rendering, needless to say, the irrelevant foam commenter irrelevant. Again.  https://www.ikea.com/us/en/catalog/products/S99903929/

At the top of the cost no object category is the Eames. https://store.hermanmiller.com/living/lounge-chairs-and-ottomans/eames-lounge-chair-and-ottoman/1000...
But there's a hundred out there just like it, everything from $100 crap all the way up to better than Eames just minus the price tag. My fave is the Ekornes Stressless with Ottoman.