Nostalrius Begins - Quality wow vanilla realm (1.12)

Hi,
As I'm new to Vanilla, I'm unsure which of those specs I should roll, and since it's gonna be a long journey, I'm only planning on having one character.

If you've got experience on how these specs work at lvl60 in PvP, can you give me some feedback?
I want to be good, and at the same time have fun while playing it.

Also, how to get gear once we reach 60? Is there any PvP gear available?

Thank you

Elemental Shaman's a lot of fun once higher tier content's released (AQ40/Naxx) because the itemization starts to really let them shine. They primarily play a support role in group PvP (healing, purging, and totem placement are your priority) until they find an opening to go extremely offensive. By extreme, I mean in full gear on another server it's pretty standard to two shot an FC in WSG like it's nothing.

Shadow Priest's fun for the same reason it always was in vanilla: it's ridiculously overpowered in the right hands and it's amusing to read the whispers of players that log on their alts to cry about how you're a scrub for playing an OP spec. (Frost Mages are my favorite - should never lose if they have half a brain.)

Can't really tell you anything about Warlocks.

Shadow priest and warlock are the 2 most stronk classes u can get in pvp on 60. IMO a skilled shadowpriest can beat pretty mutch anything

Locks gonna be easiest to gear in pve content. Shadow priests probably hardest because its a niche hybrid spot and elemental shamans in middle because ALL shamans will want offpiece elemental gear to pvp with. Spriest are most wanted because priest only class on horde that can dispell. It will be much easier to get into premade groups as spriest. Spriest probably strongest of the three in solo/roaming potential. Warlock probably hardest of three to play. Shaman more of a support class with good burst.