Ever since I bought the first console (Coleco Vision), I am hooked with Mario games.
It's no exception when I bought the NES, I got all of the Mario games.
When SNES came out, I bought the system mainly for Mario games as well. And so far, SNES has the best Mario compilations -- Super Mario All Stars + Super Mario World.
Sure, the N64 has Super Mario 64 and I love that as well. However, comparing the N64 with the SNES, the SNES is just a better deal for me -- much more good games on the SNES than the N64.
Final answer: My favorite console is the SNES.