The reality of which side (horde or alliance) typically wins in PvP is very dependent on which grouping of servers it rolls into. If you are looking to PvP, I'd definitely do some research into which faction typically does better on that particular server before committing. We seem to hold our own in PvP on kil'jaeden, but we're alliance. Good luck - the scroll deal is a great way to renew the game for you.