On another SE site, I answer far more than I ask. There are some questions in personal finance that have no "exact" right/wrong as it will often depend on one's experience, level of risk, etc. When it comes time to accept, I suggest two things,
(a) 24 hours. Even the Personal finance Stack is world wide, US heavy, but people from all over. Math is universal, and hopefully we'll have people from literally all over the world participating. If you accept an answer too fast, you discourage others from offering their own answer. Some might, but in general, fewer new answers come in after 'accept.' I'd not assume that people are on throughout the day, but just a small window of time, a bit in their evening.
(b) Your concern was which to accept. The votes should help a bit as it tells you what others thought. With multiple answers that are close, you just need to read them over a few times and ask yourself which is more likely to help a reader in the future. Keep in mind, those with great answers that weren't the picked accepted answer won't be offended.
(c) I asked on PF.SE.meta, regarding downvotes. The parent system doesn't force a reason (e.g. 'incorrect facts'/'doesn't address question', etc), nor can each group from what I understand. I find it kind to tell people why they got a DV. My first question was getting close votes as I messed it up, but comments alerted me to fix it. A downvote can be flipped after OP edits, so in my opinion, a DV should have a reason to help guide the writer to improve. As educators, we should all be happy to help each other improve the dialog on the board.