"It was a bright cold day in April, and the clocks were striking thirteen."
That's got my vote. There's certainly no shortage of great openings of famous and feted books (Fear & Loathing in Las Vegas, A Christmas Carol, Slaughterhouse Five, Something Wicked This way Comes, etc), but Orwell's opening is impressivley simple, using just one word ("thirteen") to immediately communicate that there is something different about the world he is bringing the reader into.
Discuss amongst yourselves. Or not. Watch someone get cock-punched by a kangaroo on youtube if that's what you feel like doing. This is America, after all.