the ultimate robotron joystick: happ P360, with kowal's mod, 4" wico shaft, and springs taken from happ supers. see the page linked in my signature line for lots details and links. also
click here for a dissertation on robotron joysticks.
other simpler, cheaper, and usable alternatives i've tried:
- ultimarc U360 with round restrictor
- happ super
generally, the characteristics you're looking for are:
- 8-way (or 49-way or analog)
- round restriction
- tight engagement (= small center "dead zone")
- the right balance of diagonal vs up/down/left/right
- not too much spring resistance
imho, if you're serious about robotron, you really should try the p360/kowal. the original wicos, with their leaf springs, can probably do as well if perfectly tweaked (and periodically re-tweaked), but i'd rather not fuss with them. the p360/kowal is as good as it gets, and is perfectly stable.
i don't know if kowal is still selling his mod, but if not, it's just a simple metal cylinder, which any good machine shop can make for you.