Should I buy the Shure SM57 or SM58 for instruments and vocals?

The SM57 is an instrument-focused dynamic microphone, with a best new price of £104 in the supplied listings. If you're shopping primarily to mic instruments, it's the more directly matched choice of these two.

The SM58 is a dynamic cardioid vocal microphone, so it's the clearer starting point if singing is your main job. Those intended roles are a useful buying guide, not a claim that either microphone can only handle one task.

Buying second-hand? The Best-value used microphones list is a sensible place to compare options. Ask about condition and check that the microphone works properly before committing; a used listing isn't automatically better value than buying new.