II and V easily. V for the reasons people have discussed in here already, plus the self-proclaimed "elitists" of FF who grew up on the localized games overlook it simply because they didn't play it when they were children. FFII was somewhat ahead of its time to me with the name-recognition system, guest characters, and a character development system with a level of depth that wouldn't be revisited until FFVII's materia (or arguably FFVI's combination of accessories/espers/equipment character building or FFV's jobs+equipment palette).

I would also actually say FFVII. Certain circles within the FF community desperately struggle to fabricate arbitrary critiques, even 13 years after its release, for the sole fact that it's more popular than their favorite game, and also out of childish impulses of competition. At the same time, many of its biggest fans don't appreciate it for its strengths, only because of the nostalgia factor. It's very rare you get real discussions about the literary themes & techniques which it introduced to gaming at the time, or the production values which exceeded nearly every game before it.

Gotta love VII!