Mine both used patient. For me, it does not matter. I don't feel inferior relative to a doctor that helps with a medical condition and calls me patient, or anyone else who provides whatever service I pay for, lawyer, financial advisor, whatever. I do expect all of these to care about what they do and do a decent job. I do not expect any of these to protect me or provide safety other than whatever protection a good service and performing good procedures will achieve. I think costumer would also work for me, better than consumer. I use client here on PC because most people do. I do see therapy as a business transaction in general, just the material to work with is some personal life stuff.