IT's one of two options. Final Fantasy, because there are a lot of them and a fair variety, many of which are awesome.

However I think I'm going Shin Megami Tensei. So many fantastic RPG's, but two SRPG's I'd rate higher the Tactics with Devil Survivor, and Persona 3 and 4 stand as a couple of gamings best RPG's. Not to mention the main SMT titles, IV being the only one I've played through really.

But FF's shear volume gives it a close second.