require(leaflet)

m <- leaflet() %>%
  addTiles(group = 'OSM') %>%
  addProviderTiles(providers$OpenTopoMap, group='Topo') %>%
  addProviderTiles(providers$Esri.WorldTopoMap, group='Esri') %>%
  addProviderTiles(providers$Stamen.Toner, group = "Toner") %>%
  addLayersControl(
    baseGroups = c('OSM', 'Topo', 'Toner', 'Esri'))

m