Apart from raiding, heroic dungeons, and achievements, the life of a level 80 player in World of Warcraft consist mainly of doing daily quests. Unfortunately all dailies aren't created equal, there are differences in both rewards and how fun the quest itself is. Which is okay if the quest isn't fun and the reward is bad, because then you just skip that one. But some quests have "must have" rewards, and are badly designed and annoying to do.
My least favorite daily quest in the game is Blowing Hodir's Horn, a quest in which you need to kill 5 Niffelem Forefathers and 5 Restless Frostborn. Sounds easy, you say? Well, it would be, if not every other player on the server would be needing the quest too. The Niffelem Forefathers don't have a fast respawn rate and are usually completely overcamped. And because everyone needs the Sons of Hodir reputation this quest gives, there is an enormous amount of killstealing going on. So much that I decided the best change in patch 3.0.8. for priests will be that if you pull with a debuff, the mob will now count as tagged for you. No more me pulling with Shadow Word: Pain, and getting the mob killstolen away from me. You know a place is bad if the priests start pulling with Shadow Word: Death. The Hot and Cold quest nearby isn't much better, you can even see people stealing the smoldering scraps another player has cooled down (bad design that this is even possible).
Good daily quests are those with useful rewards beyond money, and which don't involve competing with other players directly. The cooking and jewelcrafting dailies for example are well done. Not only are there less jewelcrafters than players, but the quests ask you to "kill any Northrend iron dwarves" or other mob types, and you can easily find a place not already camped. And then there are the fun quests, like Overstock, where you have to construct a minefield to blow up an invasion, or The Way to his Heart, where you have to mate a sea bull with a sea cow. Those only give money, but at least they aren't the usual kill 10 mobs quests, and you're not fighting other players for some mob spawn.
So, which are your favorite daily quests, and which are the dailies you hate?