The advance version is far superior. The dialogue is far more enjoyable, graphic enhancements were made (if only on the backgrounds during battles) New job classes (though admittedley nothing special) And a new dungeon which is enormous and filled with epic boss fights. Not to mention a "Boss Rush" where you can fight almost all the bosses one after another.

I'd advise regularly changing your job classes. There's no point in mastering a mage when level 6 magic doesn't even become available until near end game, and the idea is you learn jobs from one class and carry them over to another, so learning as many abilities as you can will let you create endless possibilities of party customization