I don't pack a chair, yet.  Well, on lazy no portage trips sure I'll pack a deck chair.

Here's one I recently saw & used.  Comfortable.  Super light.
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heh, just notice the post above.  2 votes for Sling Light.

Also another option is one of those Thermarest chair conversion kits.

If you sit still, I don't I fidget and fuss, you could try the nadachair   (You need to Login or Register.  It's not a chair.  It's a sling you hook around your knees and it supports your lower back forcing good posture.