You should accept the answer that most accurately answered your question, but assuming there are a number of equal but distinct answers then there are a few ways you could go...
- Choose by score (this is essentially deferring the decision to the community)
- Choose the answer you actually used to solve the problem you had
- Choose the answer you imagine to be most helpful to others
- Choose the earliest answer (not the best metric to be choosing an answer on really)
- Choosing the lowest scored but correct answer a.k.a the sympathy accept (not the best idea IMO, you may be helping the answerer out with +15 rep but you're probably not helping future readers)
- ...pick number out of a hat?
In truth it's completely up to you, but try to pick the most helpful answer (or my answer... choose my answer).