Douglas DC-4 / DC-6 / DC-7
The Douglas propliners are among the top of the piston engine age, together with the Lockheed Constellation and Boeing Stratocruiser. If you like the Douglas DC-4, also known as C-54 Skymaster, you also like the DC-6 and the DC-7. That is why I have put them together in one chapter.
I cannot say which one of the three I like most, but why wonder about such a question? Just enjoy the beauty of these aircraft and the sound they make. I haven't heard enough of this sound during my life, I must admit. I was born too late for the heydays of the piston-engined airliners, so I have seen only a small number of Douglas DC-4, DC-6 and DC-7 aircraft and an even much smaller number of them I have seen and heard flying.
Most aircraft I encountered were in the final days of their life, in use as freighters and fire-fighters or in non-flying condition being cannibalized for parts. But that doesn't make them less favourite to me.