I would also say Filial Bonds, while he did show up for me, he did so close to a beach when I was high above. He was killed by something else, which updated the quest but when I managed to get down there his corpse had disappeared. But to be fair, I suppose though that was my fault really, since at that time I thought it was a smart idea to just use one save per character. Let's just say I've learned my lesson... But still, why did he had do spawn so that I had to climb down a glacier (and die) in order examine his body?
Other than that, I would say pretty much any quest or miscellanous objetive that doesn't give me the option to give the finger and say no. I've always thought it to be annoying, especially in the case of Clavicus Vile's quest, since I have to say yes to the blacksmith in order to trade with him. That's just dumb...