now im going to tell you why Vaan is best boy:
Because it's an OPEN WORLD GAME. ff xii devs were insanely ahead of their time to have an MC that's not directly bound by the main story progression. Of course Vaan has the visions of his brother etc but mainly he is a guy that wasn't to be a pirate. Going for sidequests is literally part of his character.

Meanwhile going on side quests became a meme in modern games because you can't a hero that has an urgent quest and you are off helping old ladies find their lost frying pan.

yes design wise reks is better.