We've done this a few times, but it boils down to a few common things.
The church's acoustics.
The ability to get the microphones to the most appropriate position.
The standard of the musicians.
The acoustics are fixed, so probably is the musician's level, and even quantity. The variable that makes the most difference is the mic position, because invariably the best place is the most difficult to achieve. Cathedral stands to get them floor mounted quite high are visually ugly, and usually these events are with an audience, so huge big stands in the centre are often veto'd by the powers that be. Catenary cable hanging may be possible, but some churches won't let you attach the cables.
The actual mic choice is not as important as getting the right place for them.
The most popular technique is one of the coincident pair systems - X/Y, or a variant, or a Blumlein pair of fig-8s, or a Decca Tree or similar, with or without outriggers depending on the venue.
Have you got any more details?
