The best replacement for openstreetmap is google maps.

The best alternatives to openstreetmap are rated as following:
★★★★★  google maps
★★  openlayers
★★  wikimapia
★★  mapquest
★★  mapbox
★  navteq
★  waze
★  google maps api
★  garmin maps
  google mapmaker
  cloudmade
  tomtom maps

Your alternative for openstreetmap is not listed? Suggest!
Speaking about openstreetmap, one probably shouldn't forget about openlayers.

Other search terms related to openstreetmap and their ratings are:
★★★★★ openlayers
★★★ leaflet
You have in mind a companion for openstreetmap and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of openstreetmap in all years. Click on graph for more.
openstreetmap
google maps
openlayers