The best replacement for yongnuo is nissin.

The best alternatives to yongnuo are rated as following:
★★★★★  nissin
★★★★  lumopro
★★★★  neewer
★★★  godox
★★★  cactus
★★★  pocket wizard
★★  speedlite
★★  canon speedlight
★★  nikon sb 700
★★  metz
★★  vivitar
★★  canon speedlite
★★  cowboystudio
★  430ex ii
★  canon st-e2
★  meike
★  nikon flash
★  nikon speedlight
★  phottix
★  neewer flash
  pixel king
  canon flash
  sb 900
  canon 430ex ii
  bower

Your alternative for yongnuo is not listed? Suggest!
Speaking about yongnuo, one probably shouldn't forget about high speed sync.

Other search terms related to yongnuo and their ratings are:
★★★★★ high speed sync
★★★★ pocket wizard
★★★ hss
You have in mind a companion for yongnuo and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of yongnuo in all years. Click on graph for more.
yongnuo
nissin
lumopro