There are many alternative milk like drinks to use as a substitute for milk. Many are made from either rice, soy, oats, almonds, or other nuts. They are nothing like the content of ingredients found in milk. Milk contains fats and protein as well as calcium and other minerals. In an attempt to be a legitimate contender for milk replacement, most add extra calcium. Some even add more calcium than is found in milk. But, without taking some extra magnesium, this added calcium hinders rather than helps health by upsetting the calcium magnesium ratio preferred by the body. chart The unbalanced (10-1) ratio found in whole milk is really only appropriate to consume in the first few years of life when cartilage bone is solidifying into solid bone and rapidly growing in size.
The best milk like alternatives are the ones with only a small amount of calcium added, 50 to 100 mg. instead of 325mg, unless you add extra magnesium. Remember to add this amount with any other amounts from foods or supplements to get overall totals. Other food sources for calcium and magnesium are available and needed to maintain the mineral ratios. Maintaining minerals ratios is mainly to protect against overworking the Kidneys which are designed to control mineral ratios.
The elimination of cholesterol, IGF-1, other hormones, and excess saturated animal fat may be the real reason for the avoidance of milk. Remember, for some children, milk is a significant source of fat in their diet and needed among other functions for skin health. When low fat milk first became available, Pediatricians saw a large increase in skin conditions develop all at once from not enough dietary fat. ref
FYI: Soy has a number of adverse potential actions in some people and for this reason would not be a wise choice for many people. There are factors in soy that hinder digestion and others than can adversely impact thyroid function. article Some of these factors are removed in processing, but why take chances?
Yes, soy milk does have the most protein. Plus, remember that milk alternatives are not a good substitute for milk in children's diets unless extra fat and protein sources are available and consumed.