Sometimes I get a good answer and accept it, but the someone else posts a brilliant answer. I of course upvote it, but I avoid changing my accepted answer in most situations, since I feel it might be a bit frowned upon, so to speak.
Is it "bad practice" (for lack of a better term) to accept a different answer after you've already accepted an answer?
If the new answer is better, yes you should re-accept.
The accepted answer is the answer that suits your needs the best.
Edit Some people accept the first answer and never touch the question again which is a shame because better answers are disregarded and it leads to frustration by the answering parties. So I should wait some time to accept and frequently visit the question for updates. First to get the best response for yourself. But more important, to leave a legacy for other users who have the same question.
Accept the best answer, even if that means un-accepting the previous.
Of course, using some common sense, also (for example, it happened to me twice already that a user went back and forth several times accepting one answer or the other, and that becomes really annoying). My advise is that you should take some time to decide which is the best answer, and act accordingly. If it is a well-thought action, then it's quite improbable that you will want to revert it again.
As a side note, I always wait a little bit before accepting any answer. I may have up-voted the answers soon after reading them, but there's always time for accepting it. Taking one day or so may avoid the need to re-accepting it later.
The FAQ says, "When you have decided which answer is the most helpful to you, mark it as the accepted answer".
For me, accepting an answer is not about which answer is the best, it's about which one is the most helpful, which is going to depend on the question. If you ask a question and somebody solves it straight away with a concise solution then it may be the most helpful to you, because it allows you to get past your current problem with the least amount of time wasted. If somebody comes and answers the question later with a more detailed explanation, covering some more of the ins and outs, this may be a better answer. But is it more helpful to you? Maybe, if it tells you something critical you didn’t already know/consider, but maybe not because you already knew some of the extra detail and your problem is already solved.
The community vote should indicate the best answer / most helpful in the general case. The accepted answer should indicate what was most helpful to the person asking the question (which is why we sometimes end up with crazy situations like accepted answers with negative scores). Only you can decide if the later brilliant answer helped you more than the early good answer...
