The falcon. Reason being is that the DeLorean at the end of the day, is also a car. So its meaning is split between two iconographies.
The falcon is the falcon. There is nothing else, there is no other interpretation, no other meaning. The symbol = the star wars corvette, pure and simple.
This was my logic as well. Going further, the design of the DeLorean is uncommon, but not completely unique. Things like the wing door are rare, but have turned up in other designs (including a Tesla). At the end of the day, it still looks basically like a car.
The Falcon, on the other hand, is fairly unique even by spaceship standards. The assymetric outline looks like no other standard spaceship design, making it instantly recognizable.