I've had good success with an AKG C2000 microphone. In post-processing, I always add the multiband compressor of Cubase with the "acoustic guitar" settings, which I think has a greater compression ratio on mid frequencies. It helps a lot at boosting the overall level of the recorded track and the default settings for acoustic guitar do the job. Some reverb is also needed if you record in a room which does not have natural reverb. Best results are sometimes found when I record in a very small room (say the bathroom) which has a lot of intrinsic reverb.
I find it it the most satisfactory setup. Recording from my piezo pickup I get less feel and attack. When possible (i.e. no background noise, good microphone, good guitar) I prefer to go with a microphone rather than recording the output of the piezo.