I have really bad knees and the absolute best, most comfortable chair I've ever spent any time in was a knock-off of an Eames lounger with the associated ottoman. A genuine Eames will set you back more than $4000 these days, I believe, but a very good chair in the same style will run less (perhaps significantly less) than $1000.
Eames chair:
https://en.wikipedia.org/wiki/Eames_Lounge_Chair