For most annoying, I'd say Atlas Shrugged. Haven't yet read Da Vinci Code, and plan to avoid it as much as I can. I've already gotten a full rundown of the Amazing Fake Secrets in the book from a friend who was briefly obsessed with it, and I don't think Dan Brown is an author you'd want to read just for his writing.

PS, I bought you Brimstone.
Oooooh thankyou. Um, do you still have my address?