Here are two related Meta links:
How does accepting an answer work?
Which answer should I choose?
- The bottom line is that you should accept the answer that you found to be the most helpful to you, personally.
Which answer do I accept if I have multiple correct answers?
(Specifically, this answer to the above question.)
I would say, the obvious 'established criterion' is yourself. You may want to mark the most humorous one as the answer. You may simply go by the earliest post. Or go by the alphabetic sequence of the usernames...
The only advice I can give is that the more arbitrary/subjective your selection is, the better it may be to actually comment on the chosen answer, or the rest, why you have made your selection as such. It's not so much to provoke a debate, but to let the rest understand your train-of-thought which we would otherwise have no access to.
If you think about it, accepting an answer is to close the feedback loop and let the rest know how the chosen answer is the most helpful to you, and I believe adding a small comment to explain that completes the completion of the loop nicely. :)
(now, I hope you will accept this answer because I'm hoping your subjective criterion consist of me ending with - please?)