I used to cook my chicken and turkey breasts to 165F and was quite happy with the results. After reading ThermoWorks' blog post on correct chicken cooking temperature (see link below) and doing some additional research, I changed my approach. I now cook lean breast meat to 155F and love the much improved results. 155F is the temperature at which I get the exact texture that I enjoy. You may choose to go a little lower or higher depending on preference, and that's absolutely fine. Note that if a turkey breast is pulled out of the oven at 155F the internal temperature will continue rising to about 165F.