I loved lightgun games on the old systems, and I think the Sega Saturn's Stunner was the best hardware of the lot. The obsolescence of CRTs pretty much killed the tech, but the gameplay style has made a bit of a resurgence a couple times with the advent of the Wii and VR.
I second the Sinden. I use it in MAME and it requires some config changes to set it up, but their support documentation on how to get it up and running is spot on. The only real problem game I've run across is Terminator 2.