This can be called completely pointless, but I'm interested. Which would you say is the most pretentious of all the mangas you've read? Animes count, too, of course.
For definition (number 1; a and b): http://en.wikipedia.org/wiki/Pretentious
Now... I found Code Geass to be horribly pretentious and I know many here will hate me for that. I just found the story to be flat, the dialogues inflated with self-importance and the characters bland. The setting was nothing but silly.
Although pretentious, it still managed to be enjoyable, I guess it deserves credit for that at least.