I’m going with the Boeing 247.

Beat the DC1 by a few months.

The Boeing 247 is the reason the DC-1, the DST, and eventually the DC-3 came about. Boeing was unwilling to make enough planes to meet demand, so airlines turned to Douglas which then built arguably the most successful airplane ever, the DC-3, and ate Boeing’s lunch.

I have never flown in a DC-3 (or C-47). That's my parents' generation. I remember my mother's tales about a flight in the late 1940s that landed in a snowstorm in DC (ironic, I know) in a DC-3. The plane plowed into a snowbank but everyone was OK.

I do remember DC-3's in the sky in the 1960s. They were the reliable mosquito killers in south Florida. They would fly low over neighborhoods disgorging their fog of insecticide ... probably DDT in those days! Always a treat to see them up close! I mean really close. It seemed like they barely cleared the trees.

Those were the days of low B52 flyovers too. Homestead AFB was part of SAC.

Another plane I remember really clearly in the skies ... the Lockheed Constellation