Due to the age of the Atari ST you'll probably find most of us were using joysticks, not gamepads, back in the day.
For those most tended to favor the original (not re-release) Competition Pro 5000, although I personally favored the Cheetah StarProbe which was also fully microswitched and had fighter plane style trigger buttons in addition tot the fire buttons on the base.
Bear in mind the ST officially supported only 1 fire button iirc.
1977 VCS Heavy Sixxer (Boxed)
1990 Atari 1040STE, 4MB, UltraSatan, TOS 2.06, TT Touch -> Atari SC1435 Colour CRT Monitor
1991 Atari TT030, 2/64MB, Int 8GB Gigafile SCSI2CF, TOS 3.06, CaTTamaran Accelerator -> Atari TTM195 19" Mono CRT Monitor
1993 Atari Falcon030, 14MB, Int 4GB IDE2SD, TOS 4.04 -> Atari PTC1426 Color CRT Monitor
Amiga, Mac, DOS, Newton, SGI, Sun, NeXTStation and more!