The best replacement for cmyk is rgb.

The best alternatives to cmyk are rated as following:
★★★★★  rgb
★★★  pantone
★★★  pms
★★★  rgb for printing
★★  rgb for web
★★  rgb printing
★  spot
★  rgb for print
★  cmyk
★  rgb color
★  rgb indesign
★  rbg
  rgb illustrator
  rgb in photoshop
  spot color
  rgb photoshop
  rgb printer
  lab color
  rgb images
  ryb
  working cmyk
  rgb what better
  pantonewhy would a printer insist on cmyk
  rgb better for printing
  pms color
  pms colors
  rgb color space
  rgb in printing
  rgb gamut
  spot printing

Your alternative for cmyk is not listed? Suggest!
Speaking about cmyk, one probably shouldn't forget about pantone.

Other search terms related to cmyk and their ratings are:
★★★★★ pantone
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Google Trends

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cmyk
rgb
pantone