Not to mention is still very comfortable, especially for its size. And it's basically the pinnacle of 2D controller design when it comes to functionality.
Best 2D controller is the Japanese saturn one. Better ergonomics, six face buttons and even shoulder buttons.
Too big, SNES's d-pad is better. The 6 face buttons on the Saturn is better only for Street Fighter, a single game. If you're that into Street Fighter, get an arcade stick.
You can still buy USB variants of the Sega Saturn controller on AMazon.