1 is seriously boring. 2 is ok. 3 sucked. 6 was good. 7 is amazing. 8 was good. 10 was the best in my opinion and 12 was good.
If you dont mind the retroness I recommend getting a playstation 1 or 2 and buying the two in one game of 1 and 2. 2 was unlike any FF and one was boring but still so epic because, its the first.