Easiest/Simpliest class for a beginner?

I think a lot of suggestions of Warlock and Hunter are based on a lot of factors that give them some amazing options when solo-leveling, but that doesn't necessarily make them easier to play. I think they rely on or employ a lot of the more 'advanced' aspects of the game that someone just coming in may not fully grasp, and thus enjoy.

Personally I would recommend a very straight forward class like a warrior, or mage (maybe even rogue, paladin, or priest). You see your sword swing, or you see your fireball fly through the air, and the enemie's health goes down. It's simple action and reaction. It's very visible, and anyone can understand it without too much instruction. Once they have some of the concepts down, and understand some more complex aspects like aggro/facing/abilities/talents/items, then they're probably going to want to try something different any way.

Now if this is someone that's played an MMO before, or is just generally good with games (you seemed to indicate otherwise on both counts), then they may not need such coddling.