Since I'm on a limited budget my choices were constrained to those books available here;
The Mysterious Affair at Styles by Agatha Christie
The Chinese Parrot (Charlie Chan Omnibus) by Biggs Biggers, Earl Derr
and
Murder Must Advertise by Dorothy Sayers
Since I've read several Lord Peter Wimsey books and several Hercule Poirot books I've voted for Charlie Chan.
(The fact that bumping The Chinese Parrot tightens the race has nothing to do with my selection. (much))
Edit; I intend to read all three this month so as to compare/contrast them.