I think I like one who is within 10 years of my age on either side. They can appreciate better the stage of life I am at if they are in it themselves or have gone through it before. I also prefer one with experience. I think at least 10 years experience would be the minimum for me. My current T is about 5 years older than I am. My first T was about 8 years younger. My PNP is 15 years older than I am, and I get on quite well with her. My family T was about 5 years older. He had a lot of teen and young adult clients, and I felt this was essential experience and interest for working with my daughter and me.