Truth to be told, there is no harder class for PvP then a druid I believe. Well, unless you want to spend your life in the Battlechicken form. I find it a lousy immitation of a Mage.
So, if you want to PvP a lot as I read you should pick something else.
Warriors are simple to play and they generally are tough opponents in PvP. Every class has its nemesis, of course, and Warrior's one is Mage. However, Warrior scales very much with gear, so good gear will increase your viability substantially. Also, Warriors are kings of group PvP. With a healer takin' care of their back (be it priest sham pal.. or druid ;]) they can really whip ***.
Mages are kings of solo PvP and crowd control. They are vulnerable to attacks, but their target is vulnerable to theirs as well (I mean, warriors deal a lot of damage and have a lot of health and defense. Mages have little health but deal shlt loads of damage).
Paladin is, on the other hand, somewhat boring yet the easiest class to play. You just pop up the right seal and bam bam bam heal bam bam ... They're good at pvp, if you got nerve to spend 10 minutes for a single fight.
If you like to be a *******, Rogues are cool as well. Sneak up on the dude, bam whoop splat, he's dead. Didn't know what hitem. Rogues with Combat Swords spec are this game's No.1 damage dealers, on par only with Mages. On the other hand, Mutilate Rogues are usually Stun Masters (they can field a 20+ second stunlock. This means they chain skills like Cheap Shot, Gouge, Blind, Kidney Shot so the enemy has no way to retaliate for over 20 seconds).
Hunters are pretty cool. It's the no.1 soloing class, because your pet tanks while you deal ranged damage. Effectively, you're a team of two all the time (after lvl 10 that is). Hunters specced in Marksmanship are also pvp kings, dealing sick damage from afar and being able to stop, snare, silence and stun their target with an appropriate skill.
So generally druids are fun, druids are tricky, druids do everything... but they can't do anything really well and the different parts of 'everything' are placed in different forms, meaning that whenever you wanna pvp, you have to switch forms a lot and mobilize all yer grey cells to win. It's very sophisticated at times.
Oh and druids start slow. Most classes get the most important toys fast - druids get theirs all over to level 70 (you can't be a good tank/melee dPS/ranged DPS/healer all from the very start eh?). It irritated me how... mediocre my druid was at lower levels. Priests heal 3x better, resurrect with no cooldown or reagent. Warriors laugh at my bear's clumsiness. Rogues laugh at my cat's damage output. Mages laugh at the balance spells as they do 2x the damage while casting spells of a different element than they are specced in. All these 'mediocrenesses' slowly wear off... but as you reach 40th level (Resto/Balance spec) or around level 60 for Feral specs.
Edited, Oct 4th 2007 8:41pm by XanNerull