Sennheiser MKH 40 by joedoc
The Sennheiser MKH-40 is a world-class small diaphragm condenser mic that continues to surprise me every time I try it out on a new instrument. I have used it for choir recordings in less-than-perfect rooms (the wide-ish cardioid pattern "dried up" the room compared to a pair of omnis), unusual drums and percussion (also excellent as a pair for drum overheads), violins, acoustic guitars, upright bass, and even wound up with a "keeper" vocal when a singer was inspired and ready to go, and the MKH-40 was ready to go in the studio. It wouldn't be my first choice for vocals, but did a fine job when put on the spot.
This microphone's one serious downside is it's sensitivity to wind/breaths, especially from the side. A nose-exhale from an acoustic guitar player can cause rumbles that ruin the take. Double up on pop filters to block booger blasts.
The MKH40 may not be cheap, but if you want a no-compromise SDC mic then put this one on the short list.