What would you recommend is the best for recording vocals for music preferably singing but also in general for recording music would it be Mono or Stereo?
Usually, when recording with one microphone, one would record as mono.
A single microphone or a single voice or instrument is usually mono. Acoustic piano is often recorded in stereo (with two microphones). Drums (which can be considered multiple instruments) are sometimes recorded in stereo or more-often multi-tracked with at least 4 mics and sometimes with a separate mic on each drum or cymbal.
Most modern professional studio recordings are multi-tracked with every voice and instrument on a separate mono track. And of course certain parts are recorded or re-recorded separately at different times.
During mixing the sounds are “panned” and placed “naturally” across the stereo soundstage with lead vocals in the “center” (identical in both channels).
There are (somewhat rare) stereo microphones where two mics are built into one body, one pointing toward the left and the other pointing toward the right. That can useful if you are recording something like a choir or a live band.