I’ve been undergoing torture all my life. These devices of the devil bend my body 90° at the waist, and then again 90° at the knees. Halfway between bent and straight. I can hardly imagine anything less comfortable.
I’d be happy if the chair-angles were either bigger or smaller. Kneeling chairs are nice, as the body/thighs angle is about 110°, which “reduces lower back strain by promoting proper spinal alignment”. Zafu is cool, because you can sit on it in many different ways, according to your current mood. Bean bags are comfortable, they adjust their shape to your shape. Sitting on the floor leaning against a wall with legs stretched out and a small pillow under your back is almost as good as sitting on a bed of leaves leaning against an oak.
But Aeron? No thank you.