If you are going to spend hours of your day on a computer, then you want the best ergonomic set up possible. Read this very helpful infographic about equipment that takes care of you.
Of course, as an Alexander Technique teacher, no one chair, mouse, or keyboard is going to save you. Ergonomically sound equipment will support your awareness and conscious choices of how you want to live and move in your body. If you are not paying attention to your body, you are going to hurt or at least stress your body. Your posture and breathing are your first priority, then your equipment can truly help you stay pain-free.