The Herman Miller Mirra 2 chair works for small to mid sized individuals. The adjustable seat pan makes it useful for individuals needing a smaller seat pan.
The Loover chair by Global provides a very adjustable chair for medium to larger sized individuals. The high flexible back allows for air circulation. The arms move with push button locks for each position.
This is a popular chair for moderate sized to petite individuals as the arms move in close under the shoulders and the sliding seat pan allows the seat to change from medium length to short. The chair can be adjusted low enough for most people to sit with their feet on the floor.
The Swopper Air chair is a solid replacement for an exercise ball chair. It is tension height adjustable. For most people it may not be a good first chair as it does not have back support as configured. With the wheels it also sits up higher and may not work for shorter people because the seat does not go low enough. The chair is a lot of bouncy fun.