>>713413968 (OP)4, 6, 7 (original), 9, and 10 are all great places to start
1 and 3 are good places to start as well but will have less of what a modern audience is looking for in a JRPG
2 is one of the hardest RPGs ever made, do not start there
5 is an excellent game on its own but storywise is a step down from 4 and its presentation can't hold a candle to 6
11 and 14 are MMOs
13 is a rough gem at best
15 is compromised
beyond 15 it's increasingly not Final Fantasy
so in conclusion, play Final Fantasy Mystic Quest for SNES. It's designed for the entry level RPG player, has charming if simple characters, some unique gameplay elements, and a fucking awesome soundtrack comprised of ballads, marches, and speed metal