I've gone through about all the internal hardware revisions on the original SNES and they all have poor RGB picture quality, some are better than others, RGB on the original model SNES is very blurry for some reason. Every Super Famicom I've come across has the same problem.

The SNES 2 or Super Famicom JR. on the other hand, when properly modded offers the best RGB picture (it does not output RGB out of the box). A huge improvement. I prefer the look of the original SNES/Super Famicom, but use a Super Famicom JR. because of the much better RGB picture quality.

I use a Sony standard res. RGB monitor, but the difference in picture quality can be seen on everything from RGB/Component converters to the XRGB units.