I just asked a question and three people gave 3 really good answers. Each of them is very useful and both the comments and answers help clear up a lot of things. How do I then go about choosing which answer I accept?
There are no rules stipulating how you make a decision: choosing an answer to accept is a very subjective issue.
Now, if you really cannot choose, one option (which I use myself in other Stackexchange sites) is to flip a coin (roll a die etc.) and randomly choose one. Then leave a comment on the other answers saying that you appreciated the help, but software limitations allows you to accept one answer, and so on and so forth.
For a lot of the users here, the primary functions of the check-mark is
- To indicate the question is solved
- To thank the answerer.
For those users whether they actually get the 15 rep point isn't that important: they would be perfectly happy knowing that their efforts are not misspent and you found their help to be useful.