I like FF, and call myself a fan, though I haven't played every one of them. But I'm particular about them and some just don't grab me like the others. I loved FFX for example (despite the lack of world map freedom) but the sequel I found to be awful and just undid everything the first one set up. I wasn't able to get into FFXIII either and I have FFXII on the shelf but I've not fully completed it yet (battle system is... overly complex and the movement of your characters doesn't really seem to help so much. The only reason I could see for being able to move around freely in a battle is to give yourself a slight advantage with say, a long-range leader like Fran, luring the enemy attention so the others can attack it while you stay back. It seems to be pointless with bosses, though).
VII to X are my personal likes. I can put them on and just completely relax while playing them. (Probably because I know them so well I'm hardly ever in any danger of dying, lulz).
I thought Vivi was a good character, and a neat way of portraying the black mages as a sort of unfortunate, innocent, self-aware 'species' of their own in 9.