Please do not take this as another what class I should play. I do not have the BETA and don't have access to the PTR.
I've read a lot about range getting a lot of buffs and having an advantage in PVP in MoP. I have never been very competitive in PVP i.e RBGS or Arena. I'll probably queue for Arenas every once in a while to get CP capped. Other than that I ain't looking to break into the high ratings.
I love PVPing on my Paladin and she is my current main for PVE as well and that is going to stay irrespective in MoP.
However, I have a druid and am levelling a DK currently. Well it was between a DK and a warrior and I came to the conclusion that a Warrior is a just a cheap man's DK which is a cheap man's Paladin. And also I get to skip 55+ levels of levelling through.
So I am currently deciding between a Feral Druid or a Death Knight. I would have probably gone Feral if things were as it was currently however with Ferals finally getting a separate DPS and Tanking tree things have changed a lot. Druids probably will have lost a lot of survivability from switching to Bear Form and making use of their mastery and level 50 current talents (savage defence?).
So I was wondering what class looks good for "casual" PVP or just pick up groups and the odd WPVP adventure.