The most detailed study was done by W.W.Gill and published in his Third Manx Scrapbook - an extract is given here; the fullest list is that by Kneen. A booklet containing many was published in 1923 compiled by Wm Cubbon.
In the early Manorial rolls the most common personal name (male - fewer female are found) was John, second was William (half as frequent as John), followed by Donald (a third as frequent), Thomas and Patrick (about 25% frequency of John).
A discussion on sources is available.
Cubbon lists Christian names of Men and of Women as appendices D & E to Talbot's translation of Manorial Roll 1511-5. He also produced a small booklet showing how the name arose.
J.J. Kneen Personal Names of the Isle of Man 1937