Eric,
I'll use whatever mic gets the job done, in whatever configuration works. Having said that, my favorite microphone for classical work is the Sonodore RCM 402. It is a small diaphragm omni. But I have used a wide variety of mics over the years, Brauner KHE, Neumann SM2, AKG C24, CS-1, Neumann M49, Schoeps M221B, Sennheiser (I forget the model #s), Simpson Model A and more. While I prefer the 402s, all of these get used as needed. The Model As are in their own class as a very revealing mic.
Barry