I'm a permanent Final Fan since at least 1993, and I have to say they missed the mark on XIII. They forgot what makes Final fantasy great, right down to the music. The battle system is pretty cool, but is not as nuanced as it could be, and the Summons/ultimate techniques present in previous versions just aren't powerful enough and amazing enough to worth earning. The weapon and armor leveling up system, while obviously deep, lacked some sort of satisfaction for me. Some of the visuals are absolutely beautiful, though, and it is a testament to the game that I actually stayed with it and dedicated time to it despite a lot of the Final Fantasy soul being completely absent from the game.
Oh, here is my ranking:
VII
VI
VIII
Tough decision, because hour for hour I re-played VIII more than any of them. But VII was the one I truly mastered to the point of freezing the game when opening my file. Something completely magical about that game that will forever be unique. VI - Love at first site. An RPG that hasn't even been touched imo so far. re-release it with modern production values and it is the best game, period. The music from that game will never be bested.