I've done it all (or at lease most of it), and it all sounds good if done right. I don't get caught up in a particular technique or mic/preamp combo anymore. Now I just let the songs tell me what they want (space/reverb, tonal balance, size of stereo image, etc.). Then I try to create that sound using the tools and techniques available to me.

I dont think there is one particular answer. Depends alot on the room and guitar and new strings help. Some times i get good results with x/y, other times i have a mic about 12 inches away from the guitar pointed at where the neck joins the body. I have also just started placing a piece of hardboard under a chair and placing a single mic over my right shoulder. In the mix i have also tried doubling the track and panning one hard left and the other hard right. Good luck

This is how I usually do this:

One single mic (yes it will be mono) placed where the neck begins at body, angled down towards the hole (not directly at it) from about 20-30cm (8-15"?)
or placed a closer to the hole, directed towards the neck,
depending on the sound you want and the guitar itself.

Angle about 45-60 degrees. I think... never measured it.

The stereo set up for this would be x-y pointing at named places.

I second Mr Phils' technic. I've had good results also with micing an acoustic were the neck & body meet or in that general area. Too close to the hole seems to yield more of a boomy tone of course. With the addition of a second mic, you should have a very decent overall sound.