I'm a big believer in ergonomics and just about any cheap office chair will give you a better seat than what you are using. Keep in mind that a chair is not a set once and forget type of thing, if for no reason other than the gas cylinders will actually wear out faster from lack of use than from use. Adjust your chairs as needed, each day we are just a bit taller or shorter or whatever than the day/hour before. You didn't mention but I love a moveable chair with roller ball wheels more than a standard type chair.
I prefer a well stuffed steno chair (armless). I was a trained musician and still never sit all the way back. For my hubby, he wants a chair with a back. You need a height adjustment at a minimum, and you need the right width/length of seat. Preferably you will be able to adjust the tilt of the seat, and the back if you have one. For those of us who are larger, it makes a big difference -- get the bigger, heavier duty chair. Chairs have weight ratings, most are for less than 300 pounds, some cheaper chairs less than that.
I have a long torso and relatively short arms and lengths. My seat is lower than people expect (because of the torso) but my correct keyboard height is table top and not the keyboard drop -- those are always too low for my short little alligator arms. You can really tell my short legs by my car seat, to get to where I can pump in the brake at full, I have to be right under the steering wheel.