Just started playing WoW again and I dont know what class to be, a Warlock or a DK?
Depends what your style of play is and really what you like, if you don't like certain aspects of either class then don't be them as you'll just want to delete the character.
I actually have a warlock and Death Knight and love them both as far as playing goes. Even though the lock is a cloth wearer they are still powerful enough to be able to solo most any quest. Plus you have the added minions that can be summoned. The DK is also fun because you start at lvl 55 and you have a starting instance area where you learn your abilities. You will also get your epic mount by around lvl 56 just by doing a couple easy quests. Really the choice is up to you though.
I really like my warrior! But am getting a little tired and do occasionally play my preist too
Personally I have a Death Knight, Shaman, Warlock, Mage and Priest. I enjoy playing all of them. It really is a hard choice and it really depends on personal preference. I like 'em both, but what you could do, is asking yourself these simple questions:
Do I prefer heavy armour, or light instead? Do I prefer grinding to questing or vice versa? Do I prefer tanking/DPSing via ranged or melee? Do I prefer tanking or DPSing? Which class fits my very own personality more?
These questions really helped me at the time I had difficulty choosing in-between the classes. You should try to ask them yourself as well. Hope that helps.
Formerly known as Graeme and Arld.
Warlocks are pretty decent at PvP. I however if you are just starting out, would go with a hunter. They are fun and easy to play, and have a high survivability. Making questing lots easier.
However, if you want something that is versatile, stick with the pally or Druid. Both are capable of doing basically anything, but the versatility comes with the price of complication.