The best Farming class is Chunin; hands down. However, for non-rare classes, the best ones for farming are definitely Royal Battlemage or Darkblood Stormking. Pyromancer is not that great at farming as only one skills can hit multiple enemies. Shammy and Evo Shammy aren't bad farming classes but aren't the greatest either. Troll Spellsmith is a nice class but not that great for farming. I know you can do massive damage with the first skill, but that is the only skill that can hit multiple enemies. That skills also has a long cooldown, which makes it inefficient for farming. Elemental Dracomancer isn't really considered a farming class but can be used to farm. I think Elemental Dracomancer is more fit for doing story lines since it it best a fighting several enemies quickly rather than constantly farming multiple enemies.
Now to answer your question, Evo Shammy is probably the best out of those. However, I would recommend Royal Battlemage or Darkblood Stormking over Evo Shammy.