The drafts I've know have all been easy going and sweet, not to say that there aren't those with "attitudes", but the same can be said for any breed of animal. They all have their own personalities.
Allegro, my Percheron, is a big puppy dog and thinks he's the size of a Chihuahua. If he could, he'd be a lap dog, that's not to say that he hasn't had his moments.
He tested me quite a bit when I first got him - tried to drag me around, didn't have much respect while leading, would pin his ears when asked to do something he didnt want to and even threatened to bite a few times. He wasn't bad, but he did test me. Now he knows who the boss is and he's a big marshmellow, who loves,loves,loves to be petted.