A hard nut to crack, but I'll choose Sir Arthur Conan Doyle the writer of the Sherlock Holmes series.
He knows how to capture the attention of his reader's. Alongside his realistic plot and dialogue throughout the entire book.
Who you got?

Homer is the greatest. He wrote Iliads and Oddysey.

In contemporary world. Sir H. Rider Haggard was greater than Doyle.

Haggard wrote "She", "Allan Quatermain" and "King Solomon's Mines"