i want a shadow priest

Oh, definately. If you're not the healer type, then Priest or Druid isn't the class for you, but don't go rogue or hunter unless you just can't stand the other classes. In my guild, mages and warlocks seemed to always be in pretty short supply, though that may not happen universally; I know that guilds are full on rogues and hunters, though, because even PUG UBRS raids get broadcast as "LFM UBRS, full on hunters and rogues" . . .

It's Warriors on our server. Warriors and Rogues, but Hunters aren't really in short supply. We've got an asston of Mages in our guild, but I don't think that's very common Hordeside...

Warlocks aren't too common, though. Whatever you pick, I would recommend really reading up on it to maximize your performance. That's what guilds look for, is talent and ability to follow directions.

Priest 4tw. I just cant seem to play anything else. I find healing the most exciting thing for me right now. Then again im also class leader so maybe its because I get to yell at people.. Well anyway, hunters and rogues are usually the most common because.. Well everyones loves rogues... And hunters are the fastest levelers IMO. Also you can just autoshoot and go afk on a hunter and still be doing a nice ammount of damage... But I wouldnt recomend that.