I use mainly Gatherbuddy and I used a warlock to start with and it was pretty good, they are awesome just because of there pet and survivability and lower repair costs because of cloth. Then my next farmer was a mage with a water elemental and I can say was wow, was I impressed, they make their own food, good survivability and low repair costs. I then started botting a Paladin and they are pretty good as well, plate, kill things fast and heal. They have higher repair costs, but you find they don't die as often so it's less of a factor. I also bot some druids and they are nice because of the not having to shapeshift, etc, but I find they die a lot in Balance spec anyways (I haven't tried Feral at 85 anyways) and that brings down their time a lot. I haven't tried a DK, but from what some people are saying I think I might go ahead and see what I can do with one. Overall I prefer the Warlock or Paladin, then Mage, then Druid. Just personal preference though...