We know what Sinclair Lewis thought:
In the realm of mystery stories there are four books which everyone should read. They are The Lodger, Malice Aforethought, Bleak House, and The Nine Tailors. I am not sure but that of all these The Nine Tailors is the best.
And The Passing Tramp has some thoughts on Lewis and his list.
Furthermore, we know that Ms. Sayers wanted to take mystery novels beyond the point where they were merely "something to read on the train."
But what do you think?