The SideWinder 3D Pro is notable because Descent and MechWarrior 2's DOS releases supposed it in native digital mode - and for all the other games that didn't, the 3D Pro has an analog fallback mode that emulates both the Thrustmaster FCS and CH Flightstick Pro, with different tradeoffs (no throttle on FCS, can't press multiple buttons in CH mode because they chorded the four digital buttons for the hat switch).
Between that and the fact that the 3D Pro uses a camera sensor and LEDs to track all the analog axes instead of potentiometers prone to wear and spiking, it's a fairly well-regarded stick for DOS gaming.
However, the 3D Pro's digital mode also tends to act up if you're using it in Win9x on a much faster than period-appropriate PC. I've tried every iteration of that timing-hacked driver on my P4EE 3.2 GHz box, and NONE of them worked at all for my 3D Pro. Analog fallback modes work, but then you lose the base buttons and have to deal with the aforementioned tradeoffs.
The later Precision Pro (earlier non-USB-compatible versions of which say "3D Pro Plus" on the bottom) has a refined digital gameport mode that's less picky about faster systems, but removes the analog fallback mode entirely, being useless in DOS. Later gameport SideWinders are the same way; steer clear of 'em.
Also, important note about Thrustmaster hardware: most of it conforms to the analog gameport standard of four axes and four buttons, with all the additional functionality being handled through keyboard emulation. However, there were these Stickworks digital upgrade chips for the F-16 FLCS/F-22 Pro and F-16 TQS that would convert them into a digital gameport interface device, with much cleaner readings on the stick and throttle axes (because they're now being used as voltage dividers like a modern USB stick instead of being read in a resistive manner per IBM's cheap-ass gameport interface spec), all buttons, switches and rotaries being available as DirectInput controls, and 96 logical flags (twice that of the later HOTAS Cougar, funnily enough)... but at the total cost of DOS compatibility, so don't bother getting an upgraded set if DOS is what you want.
Honestly, though, if you have the space, I'd just drop the notion of twist sticks and go for full-on rudder pedals. It shouldn't be too hard to find a TM RCS/Elite pedal set, the original gameport CH Pro Pedals, or if you're really lucky, some gameport Simpeds. You can use them with pretty much any analog gameport joystick you desire, except those that already have a twist for obvious reasons (though there was an adapter to use Simpeds with the SideWinder 3D Pro, but good luck finding it).
