The best RGB monitor, would be color Commodore 1084S or Philips CM11342.
Both are designed and made by Philips, with similar specifications and
supports stereo sound.

Connectors: RGB, CVBS/L, Audio-L and Audio-R.
Controls/Switches: Analogue/TTL, CVBS/RGB and Saturation.

It's also the most versatile, being configurable to operate as computer
monitor for a vary of computers like Acorn Archimedes (most earlier
models), Commodore Amiga series,  Commodore 64 and Apple IIGS. Great for
other pratical functions, setup as television-only via video recorder and
usable screen to Playstation game console.

I tested it on Apple IIe without RGB card, using the standard video cable
and goes in black & white only. I don't believe color is possible.