Title says it all.
Edit: This goes for 20s and 24s.
None. I don't have one. It's not very fun to have to fight half a team of a single class but the game wasn't designed around balancing 1vs1. You take a warlock vs a hunter and the hunter probably will win, no matter how good that warlock is. But as soon as you add a 2nd person into the fight, or even a 3rd person; the aspect of the fight changes.
No one should hate any classes because you should never put yourself in a situation where you're forced to fight 1vs1. Stick with your team.
A shaman who constantly dispels and silences a Priest will obviously put on a lot of pressure on that priest; That priest probably hates fighting shamans. But as long as you have a teammate to back you up to relieve that pressure, then you have nothing to worry about.
That level 24 completely out gears a F2P and you should never win against that 24 in a 1vs1 situation in an equal fight. But this is PvP; PvP is not balanced around 1vs1. Stick with your team and that 24 will look like nothing.
TD;DR - Don't force yourself into a 1vs1 situation. Stick with your team, and every class will seem EZ; this goes to all the F2Ps who have to fight a lvl 24 or that group of hunters.
EDIT: To give a simple example:
I was doing a 5man with Earl's Hunter, Yde's Hpally, Veint's Dpriest, and a random Ret paladin who was decently geared.
I was holding the flag on top of horde tunnel for a good 5-7 minutes @10 Stacks of Flag Debuff. Their team had 5 hunters, a few rogues, etc etc; it was an Average Alliance team with overplayed classes. I didn't feel pressured at all. I had 2 healers on both ends of the Tunnel so that I had heals on me no matter where I turned. Earl stayed on the ground with them and protected them while he got healbotted. Obviously any Flag Carrier with 10 stacks makes you want to overlook their teammates; people mainly targeted me. However I had my teammates to help me. We easily won that game. Of course this is a 5man and maybe 1/3 of the alliance team was undergeared(or not 100% BiS geared) and at least 5 of our team were well geared. Stick with your team, and you'll win.