>>723503957 (OP)
III or IV are probably better starting points because they're where some of the biggest series staples came into play. And while I wouldn't say you should play I on the NES(at least without researching it a bit first), the GBA and later remakes aren't bad either. V is the game that really cemented the concepts of the series' job system(though this system isn't used in all the games either).
VI is somewhat odd in that the first half the game is linear, while the second half has some mandatory bits but otherwise gives you the option of doing everything or trying to instantly brute force the final dungeon and boss. Each character has specific abilities, but you get the option to teach anyone any spell you want.
VII decouples the job system from characters turning everything into equipable crystals that level individually and can be swapped around depending on who you feel like using(it also has the most barebones itemization of the entire series).
VIII's gimmick is that you get all your magic by sucking it out of enemies, gaining uses of that spell rather than having MP. You can use them up as a limited resource, but you can also attach them to a character's stats to boost them instead, with the more of a spell you have = the bigger the boost.
IX is basically a return to III mechanically, while also giving each character a very defined archtype.
X and XII both have a large board that allows you to unlock various stat boosts, the spells, and abilities. Each character starts out in a particular place on this board, making it easier for them to be built as a particular job, but also gives you the ability to branch out or go an entirely different direction if you're willing to grind.
XIII and XV both suck. They suffer from poor writing, and have combat systems that take away a great deal of your control from battles outside generalizations.
XVI is "Final Fantasy decided it wanted to be both Game of Thrones and Devil May Cry today."
