In WoTLK I'd pick a paladin, a retri or a holy one for my main. (Holy 17k heals ftw, Retri 6k/7k burst damage AND nice heals.)
But if I was to choose between a warrior and a druid, I'd base my choice on my game experience.
Druid is not that hard to play, every form has its own benefits, you just switch whenever you need to stun/heal/deal some damage.
Warrior is a difficult class to play. You need to time your moves and stance changes PERFECTLY. For example pummel, you need to pummel RIGHT when the enemy begins to cast or else he can press escape (pseudo-cast) and make you waste your pummel, so he can deal some unstoppable damage. Or Spell Reflect, he can do the same.
If you like exping and owning in arenas ( Druids are the first targets in arenas ) , I'd choose druid
If you like owning in BGs, Arenas and Duels but having a hard time learning the secrets of the class, I'd say warrior
GR: O druid einai san tous caster re paidi mou sto L2. Sxetika eukoloi kai gamane. O warrior einai san ton gladi, prepei na eisai maestros sthn class alla ama thn ma8eis kala , gamas kai derneis kai tous koveis olous ane3eretws.