As much as various media outlets and so-called experts would like you to believe there really isn't any good research on what the best diet is. However there are some principles of a healthy diet that we do have good research on. Getting roughly 1 gram of protein per pound of ideal bodyweight per day is usually the best place to start. Then backfilling in the rest of your calories with carbohydrates and fats as you see fit. As to the specifics: meats, dairy, fruits, vegetables, potatoes, rice, etc. are all fine. What matters is that you find something that allows you to stay lean, enjoy what you eat, digest what you eat without feeling ill, and it must be sustainable. There are no magic diets that work better than others. The goal should always be calorie control, enjoyment, getting in a good amount of nutrients, and to make it as easy for you to follow as possible.