Given a series of almost identical answers, what is the proposed etiquette on which one to accept? Do I go for the user with the lower rep, or do I award it based on who answered first (of course accuracy comes first)?
Usually the oldest answer get my vote.
It's up to you.
Ideally it should go to the answer that helped you the most, whether that was the first or last or whoever posted it.
Many times there are two or more virtually identical answers (and no other answers). Then you should accept the one posted first. It has actually happened to me at least three times that I have posted an answer, and just a few seconds or maybe a minute later, another user posts an almost identical answer, and leaves it there.
Every time I post an answer and notice that someone else has already posted the same information (even if there was no answer posted when I begun to write my answer), I delete my answer. But most users do not; hence, it is good practice for the OP to accept the first answer in such cases where the options are virtually identical.
Changed italics to boldface to emphasise the hypotheses even more.
What I mean is that,
If Answer A and Answer B were posted the very same second, it doesn't matter which of them you accept.
Clarification of Clarification
If there is another answer, say "Answer C", which is better than both Answer A and Answer B, in the sense that it contains more information, is more clearly written, or is more grammaticality correct, then you should accept Answer C, and none of Answers A and B.
Let's say I post a question, and when I return a week later, there are three answers, Answer A, Answer B, and Answer C. Answer B is not very good, but Answer A and Answer C are more or less identical. There are just minor differences in wording. Then I should accept the one of Answers A and C that was posted first.
I do not mean to say anything except what I am saying above.
Choose the answer that helps you the most.
FAQ Entry: How does accepting an answer work?