The Vang Battlefield Earth by L Ron Hubbard. M any people will not read anything written by Hubbard because of his connection with certain religions. To them I say, it is a pity to let your prejudice get in the way of a great novel.
Battlefield Earth is technically a post apocalypse story.
It is set at a time about a thousand years after the event, though. The fall of Earth was not brought about by ourselves. No, it was an alien mining corporation that brought us down. The bedraggled, diseased remnants of humanity are blissfully unaware of their heritage. And most of them don't seem to care.