Windows sigh
there isnt a great answer. here is what i have used:
ps1 controller/n64 controller
both these are well made controllers, but these days we use more buttons that they have i guess. great for emus tho. you can buy usb adaptors for these gaming controllers. being usb sometimes they just work. not always, it depends on the game. in particular you can have problems configuring the digital joystick on the n64 controller in some software
macally controller
there are different versions of this, actually i dont know if its even sold any more? i had an early version. it worked ok but the digital controllers were terrible, almost pointless. might be better now.
xbox 360 wireless usb controller
this is hands down the best controller hardware i have ever used. really well built and comfortable to use. i really got it to play console-port type games under windows/bootcamp but there is a driver available for osx as well. i have to say though again how well the osx driver works is different from game to game.
its sad to say but generally if there is a game i want to use a controller with and i have a choice of buying the windows or the mac version, i usually get the windows version, just coz mostly they are specifically designed for the xbox controllers and so it all works right away
depressing news i know. i wonder if apple will ever make an apple controller. i guess not.
let us know if you find anything good!