Traditionally VIT is the main controlling stat for GLA/PLD like all tanks, but that has changed somewhat with SB and SHB's changes to the battle system and enmity generation being more passive now rather than using abilities like Flash to burst generate it like it used to be, so other stats are starting to play a bigger part in the role. VIT is still important though as it increases your HP and defense, two very important factors for tanking (i.e. survivability).

Apart from that, I'm not sure, as I'm not an end-gamer so I don't take much notice at trying to min-max every little aspect of my character. So someone else might have better advice to give on that subject.