My Official Final Fantasy Ranking
This is just out of the ones I have actually played enough of to rank. I am not going to attempt to rank the ones that I have barely touched or not played at all.
Note this is only covering main numbered entries, so no Tactics, etc.
I also am only using 1 version per game. In particular, the version I like best. Original XIV was really bad, and I don't care for original XII, but I like XIV: A Realm Reborn quite a lot and think International XII is a vast improvement, so I am using them for this list.