I chose Sultan Mehmed solely on the ratings and what previous guests had said, and I was very happy that I did.
It is the perfect small hotel in a relatively quiet location, but near everything you might want to see. It is updated, spotless, has a delicious breakfast, and most importantly, the best staff you could hope for. As all of the other reviews attest to, the friendliness of the staff, from check-in, to service at breakfast, housekeeping, etc.--all are magnificent.
Mehmet will make you feel as though you have your own personal tour guide, one who can detect your likes and dislikes. He will steer you in a certain direction one day, another direction the next day, but it is always what you are looking for and wanting to see, whether you know it or not. That is quite a feat in a city of 15 million+.
I would not hesitate to stay at Hotel Sultan Mehmed again.