Confession time: in English-class in school we read Priestley, Golding and Shakespeare, only Golding wrote novels but he wasn't American. And at uni I did manage to get bye with a single course on American literature in which we read Arthur Mervyn which I found really really boring.
When we come to non-classics the only American author I really enjoy is Elizabeth George (well minus her later books) but it feels weird picking an American Author who writes books set in London for this question. I also like Jim Butcher but while the first few Harry Dresden-novels weren't bad they don't quite qualify for all time favourite.
So again I'm sort of grasping at straws and name the only American novel I've read...but I genuinely enjoyed Catcher in the Rye.
(If you have any suggestions what I need to read to close this massive hole in my literary knowledge please throw them in my direction)