Look for models that offer massage on the entire back, not just the upper or lower back. Also pay attention to the massage modes - some chairs can simulate different types of massage, which can help relax muscles
As a programmer, I understand how it is with my back. As for the massage chair, I recommend you to pay attention to models with a variety of massage programs and intensity settings. It would be good if the chair had lumbar and neck support. For more information on choosing one, see here https://askona.com.cy/en/