What is the leading argument in your mind for the inferiority of the Alexandrian text type? “Reasoned transmissionalism”! Had any texttype other than the Byzantine more closely represented the autograph form of the text in any nt book, that texttype should have thoroughly permeated the primary Greek-speaking region of the Empire beyond the first few centuries. Any later-developing “new” texttype would fail to dominate against a presumed liturgically entrenched and widely disseminated “original” Textform. One need only consider in this regard the failure of the “Western” text to gain a substantial hold within the Greek ms tradition; similarly, one can consider the limited and apparently “localized” nature of the Alexandrian texttype.
Westcott and Hort acknowledged that the Byzantine Textform dominated the Greek-speaking Eastern Empire from the mid-4th century onward. They also noted that such dominance could have occurred only in two ways: either (1) the Byzantine Textform was the product of a formal, ecclesiastically sanctioned revision, promulgated with full ecclesiastical authority behind it (the Alands’ “Byzantine Imperial Text”); or (2) the Byzantine Textform reflects the autograph form of the text, which — under a normal process of transmission — would be expected to produce an overwhelming number of descendants “at each stage of transmission” (W-H, Introduction, 45). W‑H argued the first alternative, without which their preferred B-א type of text could not be maintained.
The W-H “revision” hypothesis generally has been discarded, due to lack of historical corroborating evidence. A “process” view is now instituted in its place, suggesting that, over a lengthy period of time, the Byzantine Textform slowly evolved into what finally becomes a relatively fixed form during the post-ninth century minuscule era. But, as Zane Hodges long ago pointed out:
“No one has yet explained how a long, slow process spread out over many centuries as well as over a wide geographical area, and involving a multitude of copyists, who often knew nothing of the state of the text outside of their own monasteries or scriptoria, could achieve this widespread uniformity out of the diversity presented by the earlier forms of text. Even an official edition of the New Testament — promoted with ecclesiastical sanction throughout the known world — would have had great difficulty achieving this result as the history of Jerome's Vulgate amply demonstrates. But an unguided process achieving relative stability and uniformity in the diversified textual, historical, and cultural circumstances in which the New Testament was copied, imposes impossible strains on our imagination” (Hodges, Appendix C, in Wilbur N. Pickering, The Identity of the New Testament Text, 166).
Other claims, such as the influence of Chrysostom, the Constantinopolitan Church, or the supposed destruction of Alexandrian mss due to the Islamic conquest, are discussed in my full-length essay, “The Case for Byzantine Priority”, available on the internet and as an appendix to the R-P Byzantine Greek nt. I might observe that, if the Alexandrian text could have been wiped out by the Islamic conquest, that predominantly Egyptian text was not widespread, but reflected only a more localized tradition; also, for either Chrysostom or Constantinople to effect such a significant change in the Church’s base text, full ecclesiastical authority and proclamation would have been necessary in order to accomplish its general acceptance throughout the Eastern Empire. No such proclamation or imposition of ecclesiastical authority seems ever to have occurred. The implication returns to Byzantine originality as the more probable cause of that Textform’s dominance within the transmissional history of the nt.