Some advise on materia distribution?

Hi.
I was making a tanking gear set for my marauder and I was wondering what's the best stats to go for regarding materia use when it comes to tanking.

6 slots for materia available (maybe I'll do the weapon later on)

HP+55
VIT+16
PARRY+21
DEF+16

are the most focused on tanking...

I'm thinking that the HP materia should be ruled out as useless since even if you were to get 6 of it you'd end up with +330 HP.
Regarding VIT, I'm not sure where the soft cap is...

So yeah, I'm pretty lost. Any advise?