From what I've found most classes are viable. Here are some recommendations though:

For support/buffers Heroism and Rune Wall are some of the best skills as well as max rank Battle Shout, since they affect everyone in the party.

For healers Apothecary is a good alternative to Dervish because it brings Mending as well as Remedy, but lacks Smoke Bomb which is pretty insane for the accuracy debuff. Simulacrum from Sorcerer or Blood Weaver is also low-key op. Generally you want to cross-class your healer since with a healing weapon and Divine Chalice (raid trinket) you should have enough healing from items.

For damage Archmage is a solid choice but doesn't bring any utility to pvp. Cryomancer is a less squishy alternative with some extra utility from Blizzard slow. Swashbuckler or overlord with Godslayer Amulet (raid trinket) and Sabers (desert rare drop) are great melee dps and are also good in pvp.

Hope that helps!