I'd recommend TA, though it might be hard to play it after TA2 which is vastly more interesting in terms of gameplay. YA1 has the better story and cast imho. Honestly, I would say RW will be the toughest entry to get into. The plot feels a bit of a retread of the Spira entries (not surprisingly since it had a few members from those games working on it) and the gameplay is fairly basic until you reach the end and the game decides to ramp up the difficulty out of nowhere because it expects you to grind the old areas to build the best items and power level your party. Vaan even gets a special sword that gets better stats every time you beat the game's super boss Yiazmat.

The Zodiac Age does change around a few things. Spells and items are placed differently from the original, so you can toss your old strategy guide if you were hoping that would help. The biggest additions are the job system and the Trial Mode which is a sort of boss gauntlet that lets you have some fun battles against the game's various bosses and mark hunts. What really makes it cool is that there are several new and original boss battles added into this mode to keep things fresh for veterans. Overall, the job system and reaarangment of all the game's items makes the game feel really fresh for anyone familiar with the original.