Maybe there is more to choosing a wedding singer for your wedding, than just their voice timbre. Here are some thoughts:

1. Will you need a wedding singer only for the ceremony, or also for the cocktail hour and dinner? If you only need them for the ceremony, a mellow voice and a downbeat repertoire might be enough, but if you need them for more, there are more qualities to look for. An average full day booking would be 3-4 hours of live music. Your wedding singer needs to have a diversified play list to cover different genres and eras. Keep in mind your wedding guests are a group of people of different ages and tastes in music and they all need to listen to some of their favourite songs. A wide dynamic range of repertoire and orchestration is crucial to not causing ear fatigue to your guests. Your wedding singer needs to have guitar skills to build a song up using a looper, adding musical layers like bass lines and riffs, to create a fuller version of the song they cover. A stripped down performance with only one guitar starts to become dull after one hour regardless of the quality of the singer.
2. Do you need a singer or an entertainer? Is music the only thing you need from your singer or do you need someone who will engage with your guests and create a welcoming atmosphere? The entertainment aspect is very important when choosing a wedding singer. People always remember how they felt and although a couple of year after your wedding day, your guests might not remember the songs your singer sung, they will remember the fact they had a great time.
3. Quality and speed of communication, flexibility in terms of repertoire, collaborations with other musicians and relative vendors like DJs to create bundles are qualities that can help your planning process.