Actually, the stick profile on the logitech dual actions is square... or so the new ones are. they are very nice...
what I have tried and like is modding old original xbox controllers. they run on usb, so all one must do is chop the plug, and follow standard usb colors (ignoring the yellow wire) to add a usb plug/pigtail. FYI irt is one of the many examples of how an original xbox is really a PC with a different case.
anyway, I personally solder and tape my cable slices for this... as long as one keeps the cable length well under 16' (no more than 14') and does a good job of soldering, they are generally pretty reliable.
there are 3rd party drivers to run these; linux has it by default, redcl0ud has the windows driver (XBCD), and the xbox HID project covers mac.
What i like about the old xbox controllers:
1. 2 analog triggers. good for racing games and fine control stuff
2. technically analog buttons... they are pressure sensitive from what the xbcd utility showed me.
3. cheap. my favorite one i did was a $3 used intec micro unit i found at a thrift store... it works great and really works well.
they do center properly... another reason to keep modding the old kind i guess.
I have driven robots with the modded xbox controllers... they drive nice.
For driving holomonic systems (kiwi, killough, mecanum, crap, etc.), i prefer the dual action layout.
links:
XBCD windows driver:
http://www.redcl0ud.com/xbcd.html
Xbox HID for Mac:
http://xhd.sourceforge.net/