CCC841 The Church's relationship with the Muslims. "The plan of salvation also includes those who acknowledge the Creator, in the first place amongst whom are the Muslims; these profess to hold the faith of Abraham, and together with us they adore the one, merciful God, mankind's judge on the last day.
(I am not discussing Orthodoxy here, because we Catholics do not regard the Orthodox as heretical: Catholics and Orthodox share virtually identical doctrines, Scriptures, Sacraments, moral law, etc.)
Of the three, Protestantism is (I would say) most similar to Catholicism because Protestants generally still retain a belief in One God who is Creator of heaven and earth; a correct belief in the Trinity; a Nicene Christology; and most of the canon of Scriptures handed down via the Catholic/Orthodox Church. Some Protestants have retained many of the historic doctrines and practices of the first 1500 years of historic Christianity.
Islam (I would say) comes in 2nd, because, as Monotheists, they believe in a single God who is Creator of all that exists, and who is the judge of the living and the dead; however their understanding of Christ is totally screwed-up, they had no belief in the Holy Spirit, and their additional pseudo-scriptures (Quran and Hadiths) are false and quite possibly demonic.
Mormonism (I would say) comes in last, because it involves (like Islam) a false pseudo-Scripture based on either deliberate fraud or demonic influence; and --- even more disturbing --- does not acknowledge one Creator and Judge of all, but rather myriads of gods and goddesses.
This is not a judgment of the moral fitness of Protestants, Muslims, or Mormons (a judgment no one can make but God alone); it is just an overview of the three creedal movements which originally sprang from historically Judeo-Christian doctrinal roots.