I run my Guard "German China Farm" with the same build for ages.
Which armor/weapon/jewelry type?
P/T/H Armor, Weapons and jewelry
with some P/T/V pieces to get a bit more health.
Weapons:
I mainly got a staff in my Hands (It's got the most awesome spell in the game in my opinion, !!12!! Might + nearly full health restored is self-explainatory.
Other weapons don't matter because staff is a must.
Sigils and Runes:
Go for Boon Duration and Healing! Your allies will love you for it!
Spells:
I mainly use shouts (their boons are just too awesome in groups):
1) Hold the Line! -Grant protection and regeneration to allies.
2) Retreat! -Grant aegis and swiftness to up to five nearby allies.
3) Save Yourselves! - Draw conditions from nearby allies to yourself. Gain multiple boons for a short duration.
4) Stand Your Ground! - Grant stability to yourself and allies.
Traits
0/10/30/30/0 or 0/0/30/30/10
=> for Toughness and Healing Power
In group fights (WvW/Dungs) YOU WON'T DIE.
They just can't stop you and your booned-up allies.