In my experience, this aspect of picking the right mic can't be underestimated. It's an emotional boost for a singer who might otherwise feel intimidated or insecure. Once everyone is happy with the microphone choice, you can pick the preamp, compressor, equalizer, or other signal path components. I know I've found the right mic when I can listen to a performance and lose myself in the singing without thinking about technical considerations. When you have the right marriage of mic to voice, it's truly a magical thing.
Microphones are like people.
Some bring out the best in others. Some bring out the worst. Sometimes they can surprise you. Sometimes one you think will work lets you down. One you think you know may surprise you.