To decide what is the most nutritious, it really depends on the type of grain used in whole grain products. Whole wheat products are guaranteed to contain a good amount of fiber, protein, vitamins, minerals, and phytonutrients. Other whole grains vary in how much of each they contribute. For example, wheat berries and oats offer significantly more of each of these nutrients than brown rice or millet. This is why looking at the ingredients list, and the nutrition facts panel can be helpful when choosing a bread. You might want to prioritize options with higher fiber and protein contents. Keep in mind that most whole wheat and whole grain breads have strong nutritional profiles, so make sure to pick an option that tastes good to you, even if it might not be the top performer nutritionally.