Which protein is better? Of course, a protein of animal origin, it is most similar in amino acid composition to the human protein than a vegetable. This protein is absorbed faster than a vegetable. Plant proteins contain a lot of fibre, which interferes with the absorption of protein.
Meat (pork, beef, lamb, chicken) is a good source of protein, but there is one drawback, it (meat) is digested for a long time by the stomach for up to 5 hours. Such a product should not be eaten at night, a strong load on the stomach is obtained, at night it should rest, and do not suffer to poison the food.
Fish protein is digested much faster about 1.5 hours, protein is good and similar in amino acid composition, also fish is cheaper from animal meat and it has a lot of useful substances iodine, phosphorus, vitamins and more. Also, animal proteins are absorbed by the body by 60-90%, and plant proteins by only 10-30%. Chicken eggs their protein is absorbed by 98%, but unfortunately, they can not be eaten a lot, the eggs contain a large amount of cholesterol. And a large amount of it is harmful to our body, although if you eat only proteins it is not scary, because cholesterol is contained in the yolks.
Milk has a good protein, but it is not enough there to drink it in litres to get enough for a bodybuilder. And some people in the gut do not have the enzyme lactose, so they do not tolerate it and get an upset stomach (diarrhoea). Sour milk can be suitable for these people, and even better sour milk cheese (cottage cheese), it has much more protein and almost all people tolerate it and have no problems. Another plus is that sour-milk cheese is digested faster than milk since protein is already curled up and the stomach does not need to spend time and energy to curl it. So I would call sour-milk cheese the number 1 product for a bodybuilder, but do not forget that you need to eat different proteins to collect all the amino acids that the body needs to build cells (muscles).
Soy protein is the highest quality of all vegetable, it is similar in meat amino acid composition, it is considered a meat substitute and in many food products, it is stuffed instead of meat, although meat is still much better. Soy contains phytoestrogens (female sex hormones), for athletes, this hormone is not needed, as it automatically lowers the level of testosterone (male sex hormone) which also takes part in muscle growth). And even now sell 95% of the world GMO soybean (genetically modified organisms).