Seeking xyz basemap catalog?

This is a cool tool that lets you check out different basemap providers and gives you the references to the tiles for your code. It's based on leaflet but could still be helpful to you. leaflet basemap provider demo

ESRI has some great base maps: ESRI Base maps (check licensing)

Mapbox has some great base maps: Mapbox Base Maps (paid service)

Mapquest has some great base maps: Mapquest Base Maps