I look for someone who I can feel I can relate to and am comfortable talking to. They need to be able to relate to you as well. Whether they have a masters degree or a PhD the most important thing is your compatibility with them.
I wouldn't go to anyone who I felt belittled or minimized what I was feeling.
Hope this helps and good luck!
I am actually seeing someone with a master's this time; saw one with a PhD last time. I think that the right kind of person to talk to you (i.e, social worker, psychologist, psychiatrist), is a personal opinion. It is who you feel comfortable with and helps you along in understanding our particular conditions. For example, I was hesitent to use a 'non PhD' this time, but the person I am using has worked with anxiety ridden patients in hospitals, is working on her PhD, and teaches at a local college with issues that relate to me. Personally, I have only had one appointment with her so far, but the main thing is I feel comfortable with her, and I can see that she genuinely cares, and even though I am struggling right now, I am going to give it some time.