Pea, rice and hemp proteins are popular with vegans and some vegetarians, but individually they do not provide a complete amino acid profile like whey protein. While soy protein does have a complete amino acid profile it is often derived from GMO soy (91% of all soy is GMO) and is not recommended by most health professionals for several reasons.
First, soy contains a class of compounds called isoflavones, which are phytoestrogens and have been shown to mimic the effects of the female hormone estrogen. High levels of estrogen have been associated with increased risk of certain cancers in both men and women.
Additionally, increased estrogen levels in men can lead to sexual dysfunction, reduced body hair, and even the development of gynecomastia (female breasts).
And lastly, soy contains goitrogens, substances that suppress the function of the thyroid gland and can interfere with the absorption of iodine which can result in lower metabolism and weight gain.(2)