- OpenStreetMap / OsmAnd for general use (about 75% of the time);
- Google Maps for traffic info, street view and businesses (about 20% of the time); and
- Bing Maps for areal imagery (about 5-10% of the time).
Google Maps is always extremely slow, but their business listings are very comprehensive due to their extensive marketing, and traffic info and street view are also expensive things open source cannot really rival.
Bing Maps runs at the speed of light when zooming and panning around the map. So much better than Google Maps, but the map's quality is not great so I just use it for areal imagery (another thing OSM does not have).
OpenStreetMap is as fast as Bing Maps and its map quality is better than both google and microsoft if you disregard business listings (at least in western Europe and the middle of nowhere[1]).
