A question has two or more answers. One answer (answer A) is either marked by the questioner or has a lot of upvotes. Another answer (answer B) is, in my estimation, better in some manner (more clear, more complete, better examples, more up to date, etc), but the A is correct as well.
What is the right thing to do in this situation? I believe the purpose of stackexchange is to provide the best answer to a well asked question. In voting, our goal should be to further this purpose. If I do not vote, nothing changes and A is still dominant. If I upvote both, the same occurs. If I upvote B only, it becomes more dominant. If I downvote A and upvote B, I get the best result towards making B more dominant. Only downvoting is unhelpful.
However, A is both correct and helpful, and had B not existed, ought to be dominant. Additionally, the author is deserving of positive reputation. B is just more correct and helpful, and also deserving of positive reputation.
Readers sometimes only see or read the top answer, especially if it is marked correct or highly upvoted. A reader would be better served by seeing B, in my opinion.
What is the right thing to do?