How i like mine:
First of all, SNES is king.
Second, customizable controls, i think all games should let you choose which key/button does what.
Third, preferably on a gamepad, if so D-pad just for movement, with the four diamond-arranged buttons, down = jump, left = run, right = attack, up = whatever else. obviously i prefer platformers
Fourth, if on a keyboard, unless the keys can be customized, then arrows for movement [we're not playing with our thumbs like on a gamepad so let's stop pretending so], and Z X and the such [ASD] for actions.
NEVER should jump be UP
NEVER should jump be SPACE
NEVER should keys such as Shift, Control, Alt and etc be used in these games.
just my 2 cents