I just had the incredible luck of getting a Helm of Saint-14 and it is wonderful. The perk lets you fill your Super Modifier slot (I've always used Armour of Light; enemies like Minotaurs can force you out pretty easily without it). Takes a little more finesse in PVP- if you see an enemy charging you, be ready to move.

As a Defender, I like the Crest of Alpha Lupi. The quick revives and Orb of Light shower from putting up my Ward of Dawn works well for me.

I Play defender and use Armamentarium in PVE for the double grenades and extra special and heavy ammo, Helm of Saint-14 in PVP for the blind bubble (I normally play Control). I have Helm Of Inmost Light as well. I never play striker, but I would go with it if you do since it gives you 2 free skills for your Super. Just got No Backup Plans recently, so I plan to try it out soon. I imagine it will take the place of Armamentarium for farming or boss fights where you can be close enough to the action to punch things.

For pve I'd say helm of saint 14. I prefer armamentarium for pvp for grenades. If you want to go class specific, no back up plans seems pretty good to me. Your abilities will be more useful than the bubble. Most people have wised up to the bubble shield shenanigans. I just use mine as a retreat to get blessing of light again as I harass the other team. I rarely camp in it any more.