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...