I still use a HM Aeron that's about 12 years old. Surprisingly it has held up well. They aren't super comfortable but I like the fact that it breaths. My kids have Aerons also and sit in them way too much. They love them. My wife likes Humanscale (she has one at the office). The Steelcase Leap is popular also. Everyone has their preference. I have heard 24 hour chairs are the most comfortable but have never tried one…
You can get prices in Madison Seating’s ballpark at a local used office equipment store, and have a chance to try the chair out and see the parts it’s been refurbished with, if any.