Yes, and I think they're both ingenious in different ways, Mona! Frankly, I find And Then There Were None
contrived because she was trying to fit the plot to the verse. Apparently she admitted that it was the hardest one to write, although I'm sure she enjoyed the process of plotting it.
I still say Ackroyd
is my favorite, although it is more accurate to say it's only one of my favorites. Five Little Pigs
, The ABC Murders
and Cat Among the Pigeons
are a few others I can think of besides Death on the Nile
and 4:50 from Paddington