I played Daggerspell (Mage PvP spec, focuses on CC and burst DPS) last time around. Daggerspell was awesome at first, but once most of the good PvP'ers figured out what to interrupt and when, the PvP rotation falls apart. They are great at 1v1, but not great in groups.
I also toyed with Primeval (Archer DPS) a bit.. I never really had the gear for it, so I had mixed results. Primevals are still apparently pretty popular these days.
This time around, I have narrowed it down to two classes:
1. Darkrunner ( Battlerage, Shadowplay, Auramancy ). This class has been one of the best melee DPS / CC builds since day 1. I remember many times "back in the day" on my Daggerspell getting owned by Darkrunners. Apparently they never really fell out of style, and are still regarded as one of the best classes for PvP.
2. Hierophant (Vitalism, Witchcraft, Auramancy ). As Healers go, Hierophant is one of the strongest classes right now. While it is not as "tanky" as the Templar, it makes up for it with CC abilities. This is a double-edged sword though. Templars can handle aggro in PvE and PvP with less risk, but they also are less useful in a fight beyond just healing their group mates. The Hierophant however can throw out some CC's and such in between heals, and I think that sounds like a more fun role to play.
The runner ups:
Fanatic (Sorcery, Malediction, Shadowplay) - Better version of a Daggerspell with more utility combos
Ebonsong (Archery, Shadowplay, Songcraft) - Strong and fun archer with stealth / song buffs
Skullnight (Defense, Occultism, Auramancy) - One of the top tanks in the game
Nightcloak (Witchcraft, Auramancy, Occultism) - Caster tank, commonly called "the anti-mage"