When buying a massage chair, consider the following factors: budget, space constraints, desired massage features (e.g., zero gravity, heat therapy, foot and calf massage), the intensity and customisability of the massage (2D, 3D, or 4D), and the track system (S-track, L-track, or SL track). Additionally, consider factors such as warranty, the availability of customer support, and the ease of maintenance. Balancing these factors will help you find a massage chair that best meets your needs and preferences.