N64 and Genesis have opposite problems.
The N64 stick sucked, but it's c-button set up was novel and still hard to replicate. The next best option is either keyboard or mapping c-buttons to X/Y/L/R.
The Genesis has a fantastic d-pad, but has issues when you want to either hit buttons precisely or hit multiple buttons at once. You can piano, but that's awkward. Really isn't that much of an issue considering its library, but wouldn't hold up now. 6-button fixes many issues, but still rough to reach from A to C.
I'd give the Genesis the edge since it doesn't have mechanical problems.
"You're sorely underestimating the power of nostalgia goggles." - adjl
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