Today we changed the way we sort answers on Stack Overflow. We no longer pin the accepted answer (with the green checkmark) to the top of the list of answers. By default, we now sort strictly by votes (descending order by highest score), and the accepted answer's order in the list is based on its score.. . . . Would you like to have the accepted answer unpinned on your site? StackOverflow.com
There is a longer discussion at the reference, but I've quoted the significant part above. Should the first answer in the list be the accepted answer (pinned), or should it be the answer with the highest votes (unpinned)?