Sounds like you have the right criteria, no arms and mesh for circulation. Also make sure it is on wheels and rotates. The first thing to go on these type of 'office chairs' is the height adjustment, so make sure it is a well made one.
I have a Steelcase Cachet, but they are pretty pricy! Great chair and I can lift it in the car for retreats. Can't sit for hours on those folding chairs!
Good Luck!