First off, this post on meta.SO should explain what a community wiki is supposed to be.
The best answer came up with this specifically as what kind of questions should be community wiki:
A question should not be marked CW if
it is possible to write valid, helpful
and knowledgeable answers which
contribute to SO.
Even if there is more than one valid
answer (in open-ended questions),
individual answers may still have
value, and so they deserve the rep
gain when they're upvoted. Marking
such a question CW just discourages
people from putting any effort into
I think the most important part of that comment in this case is "valid answer". That means answers should be correct in that they solve the issue the asker has and if another user comes along and has the same question, the answer solves their issue/problem as well. The opposite of those kinds of questions should then be community wiki. Meaning questions that have no definitive answer(s) should be wiki.
On to the question at hand. In the question, the user specifically asked:
I'd appreciate remarks on the differences between these options, and
suggestion on which would be suitable
for my need.
When a user uses phrases like "best answer", "remarks", or "suggestions" the question infers that there is no definitive answer(s) and that all answers are subjective to some extent.
Taking it a step further, if you look at the spirit of the question, it is I need help with how should do X which is subjective. If the spirit of the question was I need help solving X because X is broken then it would not be community wiki.
I think the main point is subjectivity. With the way the question is currently asked there will be no answers that are for sure correct unless someone is able to pull out statistical research on peoples TLD preferences and what they hold true in this specific case.
My concern with this is having Pro Webmasters turn into a site where questions like "What is the best web server?" or "Should I use Linux or Windows to host my website?" become flash point questions and give users a great deal of reputation for asking a popular question that does not benefit the entire PWM community simply because a voting equivalent of a flame war occurs.