Which one is better a "sports scientist" or a "personal trainer?"?

Following on from an earlier question, I have decided to hire someone to do my work out and fitness regime, at home. So considering that Personal Trainers are a dime a dozen, do various types of courses, which one would be better in this instance? A sports scientist or a personal fitness trainer? My main goal is health, then (surprise) toning up parts of my body I am not happy with. I am leaning towards the S/scientist as he is a friend of mine.