Kingdom Hearts has only spawned two games that I've actually played and enjoyed. Final Fantasy has spawned a hell of a lot of them.
Pretty much by default, simply because the FF series has waaaayyyy more good games under its belt, it wins. Besides, I don't like the KH games more than FF6, FF7, FF9, FFT, or FFTA.
Besides, the KH series is seriously lacking in the character development and general storytelling areas that FF games generally excel in.
22 medium-jumbo frets, 3 mini humbuckers, 2 single-coil pickups, and 6 steel strings of pure sex.