Logitech Dual Action Gamepad
Basic USB gamepad - basically a clone of the analog Playstation controller, but without the vibration functionality. D-pad, buttons (thumb and shoulder) and thumb sticks in the same places. Buttons are all numbered rather than having icons.
The shape is a bit different to the PSX controller - it's more rounded. This makes it more comfortable for me than the PSX pads. This pad is very comfortable to hold, and has a nice solid feel. It's a bit lighter than some people like, though.
The buttons have a great feel. Very fast and tight. No complaints there.
The analog thumb sticks are good with very accurate auto-centring and easy to feel for directions. Unlike the round pattern of the PSX thumb sticks or the octagonal pattern of GameCube's, the Logitech thumb sticks have a square pattern. This is a bit of a pain if you're trying to make circular motions.
The D-pad is round rather than plus-shaped. It's OK, but it's prone to sending a diagonal when you want a straight direction.
On the software side, it shows up as an HID gamepad. The D-pad appears as a hat switch, and the buttons appear as (guess what) buttons. The number emblazoned on each button is the HID button number it corresponds to. The left thumb stick appears as X and Y axes, and the right thumb stick appears as Z and rZ axes. Pushing down on the thumb sticks appears as HID buttons 11 and 12. So everything's very easy to set up for MacMAME.
On reliability, I did manage to displace a spring in the D-pad of an early revision one of these after about a year of heavy playing, but that hasn't happened to me with any of the newer ones (the early revisions have a glossy surface, while the later ones are a bit rougher, with a matte look).