Guild Wars 2

Hello im interesting in making a new char that i will use him only at WvW Zerg or some rarely Roam.
What i want?
I want be helpfull on zerg and not die so easy. Also i want have a decent or good damage so in 1 Vs ! not to be useless.
Thx in Advance

Any help pls? I really need your help guys . . .

Since thieves bring very little to a zerg in terms of utilities, that leaves you with mesmer.
Deadly in roaming and you can also assist the rest of your group with things like feedback, time warps etc

Btw you want survivability so… be ready with those stealth buttons

I think they are both equal in a roaming status. I would go for Mesmer and just phantom bomb the enemy ;p