A commander should stay alive as long as possible for the zerg fight. Ele, Mesmer and Thief are awesome in WvW but not to command. A thief is a roamer, the Ele provide AoE, Combo Field and Blas and the Mesmer provide Portal, veil, etc.
A Guardian in soldier gear can stay alive a really long time in a zerg. A Mesmer can stay alive even more if well traited, but in the middle of a zerg, not as much as a Guardian. Elementalist and Mesmer are still crucial to a good commander and if possible try to have a least one of each in your party and on the same VOIP as you so they can follow your command.
Thank you for the reply.
So Guardian would be the best choice for survivability. What if someone else in my party were a soldier geared guardian?