I hate joysticks and I've made several kinds of modified Mega Drive/Saturn controller for use with other systems before. There's this PC controller that I quite like - I have several already for the PC. I also have a drawer full of spare Mega Drive controllers that are unusable due to being completely worn out, so I made another "new" controller for my Atari/Commodore/Spectrum systems.
This controller is a later revision of one that originally had switches where I put mine. One is to connect/disconnect pin 5 - which lets you use it on an Atari ST. The other is to switch Up between the C button and Up on the D-Pad - since most of the games I'll be using this with have up as jump due to them being made for joysticks.
A similar one I made before from a Mega Drive plug & play system controller:
