Never played FFXII. Actually I played them all untill X-2.
When XII was released I was working a lot, and was more into PC games because of higher resolution.
EVen never playing it I'm pretty sure it is great because of the team behind it (vagrant story, ff tactics, etc).
Still waiting for an HD verion to play it.
FF XIII on the other hand, I bought, played for 1 hour and hope will never get back to it again.