Well you may not have noticed but this is only rank 10-6! I've got 5-1 coming too, so I think my general rankings are a bit different to the average which always puts VII as number 1. You raise a good point about VII and the other material but I always dismissed advent children as just fan fiction. I mean, I watched it SO many years ago and I don't recall it being particularly enjoyable.
And... too poor to own a psp back then XD
It was my favorite saga in my times of extreme vice. I played all of them until XII, then I didn't have time to follow the ones that came out later.
Honestly you havent missed out much! No 'bad' games, but none "incredible' either