Sometimes users make the best answer on the comments, what should I do to make them best answer?
If they don't bother to post it as an answer I usually put it as an answer, give them credit, and then mark it Community Wiki.
You can then flag the comment as "obsolete" so it can be removed and not be redundant.
1As an alternative approach, if someone wants to do so, do you consider it appropriate to ask the poster of the comment to make an answer with the same information? Also, do you consider it necessary to mark one's answer based on someone else's comment Community Wiki even if it expands substantially on the comment in some way? Jun 5, 2012 at 0:39
1That's just what I prefer, if you want to do the legwork and take all the rep, then by all means. Jun 5, 2012 at 0:42