Paladins in PvP is a very complicated topic. Paladins are deeply flawed in PvP combat, but in many ways the flaw is not with the paladin, but rather with the surrounding structure.
I believe that a skilled paladin has a good chance against every other class in one-on-one combat (except warlocks, no one can beat warlocks). This is especially true if the paladin plays to her strengths. The best strategy for a paladin is to be a rock, and let your opponents break themselves on you.
Let me illustrate this with my strategy for fighting mages:
- I generally turn on Fire Resistance Aura and try to close to melee range using a 2H weapon.
- The Seal I use for most of the fight is Seal of Justice.
- I usually put up Blessing of Light, and switch to Blessing of Wisdom if my mana gets low.
- When I take damage, I start healing very early (around the 80% mark) with Flash of Light. The idea is to heal through the damage and run the mage out of mana. When he's out of mana, I can kill him at leisure.
- Save Hammer of Justice until after the mage Blinks out of a Seal of Justice proc.
- Save Divine Shield (bubble) for when the mage sheeps you, but don't use it right away. Stay in sheep and let your health regenerate. Most PvP mages will start a Pyroblast when you are sheeped. You need to wait until the Pyroblast is almost finished casting, then bubble out of the sheep and take the Pyroblast on your bubble.
Anyways, following this strategy I can usually beat an equally-geared mage more than half the time. Occasionally the mage will get a string of crits and blow you away, but it's a reasonable fight.
The problem, however, is that the fight takes three to four minutes. All paladin fights take a long time. All the other classes kill quickly or are quickly killed. The paladin's strength is her survivability and ability to outlast her opposition. Unfortunately, the way the Honor System and Battlegrounds are implemented really hurt the paladin.
The Honor System rewards those classes which can get a lot of kills. Since there is no penalty for dying, a character who can kill someone really fast is at an advantage over someone who kills slowly. Every class can spec for high DPS except the paladin. So every class can rack up honor faster than the paladin.
The other problem is that a paladin has high survivability, but low DPS. However, the paladin's survivability drops dramatically if faced with superior numbers. For example, if I am guarding a node in Arathi Basin by myself, and one Horde player comes by, I can draw out the fight for a very long time (several minutes if need be). Long enough for reinforcements to arrive. However, if two Horde players come by, I will die *very* quickly. I will die just as fast as any other class would. The extra survivability does not help in that case.
(The exception to the above is if I have the bubble up. Then I can stall for 12 seconds, and then die immediately after.)
So the number of times that paladin survivability actually plays a role is a lot lower than it appears. In my view, it only makes a difference in equal number fights, which are fairly rare.
The implementation of Battlegrounds also hurts the paladin. Survivability means that you do not die easily. But what happens if you do die? You are kept out of the battle for an average of 15s. This is a very short time when you consider how long it takes a paladin to kill someone. The penalty for dying is very low and this devalues the effect of survivability. Dying a lot is okay if you can kill a lot before you go. I suspect that if the resurrection timers were increased from 30 seconds to 2 minutes (giving an average time dead of 1 minute), paladins would become much more powerful in PvP.
Battlegrounds are designed for the high DPS style of the other classes, and thus the low DPS style of paladins is disadvantaged.