Their is a few other ways.
You have the official component cable and or
Snes HD vision component cables (only works on pal GC)
I think hdmi looks a lot better/sharper, BUT it depends on what game and resolution
If you are running 240p by swiss then ossc with RGB cable looks a lot better.
If your running 480p then hdmi is better.
Their are plenty of comparison videos and images around the web.