Totally agree that it's personal preference and what number the owner wants to
have - no rhyme and no reason to choosing.
However, I have heard that repeating numbers (11/222/3333/etc) is more
desireable/valuable and better to have from a "rarity" perspective due to
there only being a very few repeating numbers in a collection e.g. there are
only 9 watches with two repeating numbers in a limited edtion of 100 watches,
99 watches with 3 repeating numbers in a limited edition of 1,000 watches etc.
In addition, repeating numbers are more eye catching and probably get more of
a "wow" reaction when someone see it. True or not, it does make sense.
That being said, each number is one of a kind in any limited edition run,
since there can only be one watch labeled "38/100". And it's also very
impressive if someone has X number of watches all with the same number.
In the case of IWC however - and very very annoyingly - they're limited edtion
runs (at least recent ones) are labeled as "ONE OUT OF 100" or 500 watches
labeled as "ONE OUT OF 500" !