Being serious about this for once. The only thing that matters is that the guitar sounds like you want it to. One mic and some well chosen treatment work pretty well, but other times maybe you need some finger noise and you need the sound of a pick, or ...............
The one thing I never do is treat a guitar as a 'stereo' source and use stereo techniques, because if you want realism, the biggest a guitar ever is, is the size of a guitar width wise. 600mm or 2 feet ish? if you make it wider, that's not real and sounds to me just plain wierd. So while I may have two mics, they'll be panned quite narrow. Just how I like acoustic guitars. Other people like wild stereo image shifts, but that's just an effect really.