Friend of mine built a nice MAME machine with Hyperspin and console emulation.
For the console emulation he uses USB joysticks to match the emulator (as mentioned above).
So for NES he has the USB NES gamepad, for SNES he has the USB SNES gamepad, and for N64 he has the N64 to USB adapter. He was of the opinion that console games could not be played well with arcade controls.
For myself on my MAME machine I've found that any console game 3 buttons and under work well.
But I do like the idea of the matching USB pads.
One tip if I may suggest, for my MAME machine, that does have console emulation with a mix of gamepads and arcade controls I have printed out 5" x 7" instruction cards that indicate what buttons used.
For example I have a 6 button layout, 3 over 3, and 3 extra buttons (POWER, CREDIT, ESC), I just indicate on the print out what does what. So button 1 is A for Nintendo, button 2 is B, button 6 select, etc.
Hope that kinda helps.............