Replace that old controller with a new SNES controller from Player's Choice.

Nintendo strikes gold again. They took the NES controller and improved the styling and ergonomics by rounding it off. They also added two more face buttons but the big innovation is the addition of two shoulder buttons. I believe the shoulder buttons were added to allow the player to control zooming or rotation in the Super Nintendo's pseudo-3D Mode-7 style graphics.

The impact this controller had is tremendous. Just about every subsequent console controller ever made by any company borrows from this design. You can see this in the chart, and you can also plainly see the similarities in photos of subsequent controllers.

For a long time, this was considered to be pretty much the ideal console controller. The only complaints people had about it were a lack of ergonomics and the fact that it didn't have enough face buttons to play fighting games like Street Fighter II.