The best replacement for rgb is cmyk.

The best alternatives to rgb are rated as following:
★★★★★  cmyk
★★★  vga
★★★  hdmi
★★★  srgb
★★★  ycbcr
★★  component
★★  dvi
★  s-video
★  ryb
★  yuv
★  cmyk for web
★  ycbcr444
  cmyk for print
  hex
  rgb
  rgba
  composite
  601/709
  rca
  component video
  hsv
  cmyk print
  cmyk printing
  pal
  scart
  cmyk for printing
  vga cable
  ycbcr which is better
  hsl
  cmyk color space
  bgr
  adobe rgb 1998
  adobe rgb
  cmyk color
  y pb cb pr cr
  grayscale
  ypbpr
  ycc 4 4 4

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

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



Google Trends

Scale is based on the average worldwide traffic of rgb in all years. Click on graph for more.
rgb
cmyk
vga