From a tech perspective, Saturn is the most interesting. Best controller Sega made, great memory device, built like a rock. Quads look better than triangles - in general, when time was spent, Sat looked better than PS.
Games were top notch. You can spend a lot of time talking about what wasn't on the Saturn, but what it did have was great. Virtua Fighter 2, Capcom Fighters, Panzer Dragoon, several Shining, Guardian Heroes, Dragon Force, Iron Storm, easily accessed games from Japan w/ the Action Replay (no mods necessary), House of the Dead, Sega Rally and so on.