😃 Javier
The Aeron chair is "the-one" but it cost and arm and a leg($400 US DLLS used). Avoid the knee-char, it's bad. The trick is a chair that moves with you, slick wheels and generous back that allows you to slouch. Check for chairs with a smooth rocking motion when you lean back. Avoid any chair that makes you feel you are nailed to it (no motion).