The best replacement for on camera flash is off camera flash.

The best alternatives to on camera flash are rated as following:
★★★★★  off camera flash
★★  speedlite
★  speedlight
★  ring flash

Your alternative for on camera flash is not listed? Suggest!
Speaking about on camera flash, one probably shouldn't forget about strobes.

Other search terms related to on camera flash and their ratings are:
★★★★★ strobes
You have in mind a companion for on camera flash and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of on camera flash in all years. Click on graph for more.
on camera flash
off camera flash
speedlite