Truly one of the best microphones to record acoustic instruments is the vintage German made Neumann KM84s. I own a stereo pair and use them all the time to record acoustic guitar and other acoustic instruments. I've owned them since 2008 and it's been fun watching them climb in value through the years. Neumann stopped manufacturing these mics back in the 80s. I had originally bought a pair of KM184 (that replaced the 84's) and they were really good but I read so many articles on how they fell short of the original 84s so I had to find out for myself and purchased the 84's in November of 2008. I instantly became a believer! As long as I record music I will never sell these mics. I'm a huge Neumann fan and use them pretty much everyday to record with. I'm also loving my Neumann U47 FET microphone for recording vocals and voice overs. I also own a Neumann TLM 103 that I use for vocal work as well.
Want a REALLY good microphone? Buy a Neumann. You'll be glad you did.
Learn more about Mark Teachey, Apple Hill Studios and the sounds/music he produces.