I don't know about Sales Numbers, but I don't remember the Saturn being an also ran. It remained pretty competitive against the N64 and PlayStation for quite a while. I think its shorter lifespan had more to do with Sega wanting to get a jump on the PS2 by releasing the DreamCast first.
If you are going to classify the Saturn as an also ran, than I would say it had the best games of the systems you mentioned. If you want to collect the actually system and games itself, go for it. If you're looking to play Emulated versions, I believe you're out of luck. I've heard that system is a nightmare to emulate.
You need a somewhat modern system for it but SSF (http://www7a.biglobe.ne.jp/~phantasy/ssf/) will run most Saturn games accurately.