Really, the question says it all. The three big WOW quest/item information clearinghouses are engaged in a fierce competition for the hearts and minds of players. Thottbot stalwarts tout their status as the simplest WOW site, with the most comments and pictures. Allakhazam is the oldest, dating back from Everquest days. And devotees of Wowhead, the new kid on the block, say theirs is smarter, cleaner, and free from the influence of gold sellers.
I used to use Thottbot, but soon grew tired of listening to inane arguments about who should get what loot. I switched to Wowhead after BC, when it became more than just a talent calculator site. I like that most of the comments are intelligent and helpful, that the site is easy to navigate, and that it's not linked to any goldselling companies. I love Wowhead, even if it does sound vaguely pornographic.
What site do you use for your WOW information? Or do you prefer to remain, as it were, spoiler-free?