Plenty of bus stops, special bus lanes, modern buses, air-conditioning, clean environment, frequent on-time schedules, and plenty of routes to take you to/from all major city areas and suburbs. No crazies and violent crime either.

Of course the city also needs to support walking the final 300-2000 ft to your destination after the bus stop. If most of your stops are some BS office or industrial zone, with roads build for cars, no shade, no shops, and nothing to do around, it's pointless.