Here's the list of classes I'd recommend if people said they wanted a char for PVP:
Priest
Mage
Rogue
Warrior
Shaman
I usually am okay with just lurking on these forums but as a 55 Dwarf Priest on a PvP server I had to jump in.
If you want a viable PvP* toon on a fulltime PvP server:
-Warrior: With recent pendulum swing buffs in effect + the happy funtime new gear they can use. Ugly.
-Shaman: "You know what would be a good idea? A mail wearing melee class that can heal, dispel and cast offensive magic while carrying shield! LOLZ" *puffpuff*
-Mage: The "Honor Contest" winner(s) were a Mage and a Rogue. Check the PvP realm stats sometime to assure yourself. Frontloading4thewin.
-Rogue: Same as it ever was. The ability to chose when/where/how/whom you engage in combat is always the greatest advantage. Did I mention a 45 second stun
and the ability to interrupt spellcasting (Kick) just for giggles?
*
Pvp combat defined as solo-ing, 3-5 man groups, non BG's.I still have a WoW sub but don't really ever play. The reason is purely based on the fact that I'm a Priest on a PvP server. I skim the forums everyday clutching my vain hope in my hand but....ehhhh.
Priests are the prime target in most PvP situations, since we are a force multiplier/fight extending agent. Add that to the fact that we're are probably the softest of the "soft target" cloth wearers, AND our only real defense or escape mechanism was five holed by the "Honor System" trinket.
I'm Shadow Tree down to Shadowform, with the rest in Discipline. I have max First Aid. I am an Engineer, with access to most of the nifty toys. I have the "Nifty Stopwatch" trinket. I have 3 sets of gear: +INT, +regen, and +Shadow damage. I buy copious amounts of Gheal potions, Gmana potions, Free Action potions, Arcane Power potions, and Shadow damage potions. In short I try and access every tool at my disposal to do well in PvP.
I don't do well.
My point. Don't let people tell you that Priests are "in the top tier for PvP'. We ain't. What we are is overpowered in the offense department for a Healing class. But we are also fragile, slow moving one trick ponies in PvP. Shadow damage
IS nasty. But everoyne is ready for you and your Fear with their trinket, Arcanite Reaper, Ice Barbed Spear and Will of the Forsaken. Fun.
If I had the sack to re-level a toon and I wanted an effective durable healer I'd go Druid.
If I had the sack to re-level the "best PvP toon" I'd roll a Shaman.
And if I was just a ganking asshat I'd re-roll a Rogue. Preferably Undead.
If I was okay with being pigeon holed as a healbot, but could grind solo PvE if I must...then sure. Go Priest.