As far as I know the accepted answer is always listed at the top in list of answers despite of the currently selected sorting tab (active/oldest/votes). The only single exception for this rule is when the original poster accepts his own answer, in that case the answers are sorted as if there's no accepted answer.
The following paragraph will describe my thoughts restricted by "votes" sorting order, but you may propagate them to the rest of sortings.
I'm wondering, why we use this exception and in the same time place accepted answer from the non-OP at the top even if that answer has less score than the other? In my eyes this is slightly confusing and not fair. Yes, the accepted answer is the answer that helped more to OP than the other answers, but why the other users should see such answer at the top (when the other answers with more score are exist) just because OP has accepted it?
As a result of the text above I'm suggesting the following:
- Sort all answer despite of accepted flag (there might be exceptions for non-logged users and OP)
- Add an option "accepted first" for any sort order (only for logged-in users, such option could be accessible on every question page or only in user profile settings) to make the site content more customizable.