I wouldn't necessarily disagree with anything above, Invuln/Stone/Shield are very strong endgame and while leveling. What I will say is that they lack a heal with a quick cooldown. Again, this can be mitigated by your team and buffs just like any other tanker primary, however, I'd argue that for +50 content, you'll find more strength in Rad/Bio/Elec/Fire. Everyone has their own opinions, that's just what I've found. Out of those, I'd prefer Invuln personally.