This is why I put my money on John the Apostle:
The external evidence from Church Fathers is significant. Justin Martyr’s famous debate with Trypho occurred in Ephesus around A.D. 135. In his work Dialogue with Trypho (81.4), he writes, “There was a certain man with us, whose name was John, one of the apostles of Christ, who prophesied, by a revelation that was made to him, that those who believed in our Christ would dwell a thousand years in Jerusalem.” Justin is undoubtedly referring here to the book of Revelation and associating it with John the apostle. Irenaeus introduces a series of quotations from Revelation with an introductory formula. In this formula, he claims that “John, the Lord’s disciple” wrote the following words in “the Apocalypse” ( Against Heresies 4.20.11). Irenaeus spent time as a young man in Smyrna with Polycarp, whom he claims knew John the apostle (Eusebius, Ecclesiastical History 5.20.6; Irenaeus, Against Heresies 3.3.4). The agreement between Justin Martyr and Irenaeus on the authorship of Revelation is significant. It finds additional support from the Muratorian Canon, Clement of Alexandria, Tertullian, Hippolytus, and Origen (Maier, Offenbarung 1-11, 25; Beckwith, Apocalypse, 338-9). Beckwith concludes, “So much external testimony to the personality of the author, traceable back to almost contemporaneous sources, is found in the case of almost no other book of the New Testament” (Apocalypse, 351).