And then you have this.
Unless you are willing to agree to that we need to start counting the thousands of Papist denominations.
Actually, comparing one church with many is not a valid comparison in evidencing the effects of their means of determining truth, that of Scripture alone being the supreme authority, as the wholly inspired word of God (sola Scriptura) versus those who hold the church is (sola ecclesia), usually with a certain individual in that church being the most supreme. Then there are those who basically argue there is no supreme coherent comprehensive source of Truth, and thus condemn both of the other two models for being judgmental (being ignorant of their own).
The former model would be restricted to those who basically fall under the historical classification of evangelicals, which in its modern form arose because of a share commitment to core truths which liberals, cults and Rome deny.
Thus they are treated by both liberals and Rome as their greatest threat, as their preeminence is the priority.
The second model is that of Catholicism, as well as elitists cults, both of which foster implicit faith in their respective magisteriums, discouraging objective examination in order to ascertain the veracity of official teaching.
Sola ecclesia does typically see greater unity, thus cults like the Watchtower Society manifest the most among their members. However, Hell also is unified, and unity itself is not the goal of the Godly, but unity in Truth.
While comprehensive doctrinal unity has ever been a goal not realized, the unity of the Spirit that does result from a common personal conversion to Christ (as damned+destitute sinners who trust the Lord Jesus to save them on His expense and merits), and Scripture-grounded relationship is greater in quality, if not necessarily in quantity, than that which is the product of implicit faith in church and office of men, and confidence in one's own merit and that of an institution, and or institutionalized faith, which engages ritual-based conversions, perfunctory professions or blind zeal.