The best replacement for radio trigger is optical slave.

The best alternatives to radio trigger are rated as following:
★★★★★  optical slave

Your alternative for radio trigger is not listed? Suggest!
Speaking about radio trigger, one probably shouldn't forget about ettl.

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



Google Trends

Scale is based on the average worldwide traffic of radio trigger in all years. Click on graph for more.
radio trigger
optical slave