Nostalrius Begins - Quality wow vanilla realm (1.12)

I am looking for a class to play as my first and main toon on this server.

I am looking for a ranged dps class to play, on horde side. I am planning to mostly raid during the endgame.

From what I gather so far :
Balance druids and elemental shamans are too weak to be considered.
Mages,warlocks and hunters are the only viable classes.

My question is - which among the above three is best for raiding ie which does the highest dps and has the best chances to get me into a good raiding guild ?

Also, what is the raiding situation like on horde side for the PvP and PvE servers ? I can see that the PvP server is heavily populated, so i should be able to find a guild easily, but the idea of being ganked every minute in the open world does not sound appealing to me

PvE server is behind PvP in terms of content that's already accessible. It may be a good thing (progressing as raids release is great fun) or bad (lvling fast and then being stuck with MC+Ony for months can get tedious), depending on your point of view. The matter of getting through the leveling stage without the endless need of fending off hordes of basement dwellers whose only life purpose is trying to piss you off is definitely something to consider, too.

For classes, the demand for hunters is always smaller than mages/warlocks. Also hunters struggle to keep up dps wise as content progresses. Once ZG and caster hit gear show up, mage/lock dps will skyrocket and you aren't catching up to that with a hunter.
Gameplay wise warlock and mage are similar - they have some utility here and there but most of the time you'll be pressing your frostbolt / shadowbolt button. Hunter is a little bit more complicated / interesting, I guess.

Mages and warlock are highest dps, if you plan on sticking around for naxx, then warlock will be highest demand ranged dps.

It's also worth mentioning that Mages and Warlocks are extremely common on Horde side since they are extremely powerful in PvP. Finding a good raid team as a Mage or Warlock will be much easier Alliance side, especially as a Warlock.

Don't roll Hunter, their damage is mediocre at best. The main reason they are brought is for kiting and tranq shot.

If you mostly care about just PVEing then I'd suggest rolling alliance since you will have blessing of salvation. Also I don't recommend playing a hunter if you just want to raid since they sort of fall off like others have mentioned. Warlock/mage is a really solid choice.