Growing up in WWII (I was 10 in 1944) the B-17 was an American icon. When the B-29 came out it was awesome. Both airplanes looked huge in the films and pictures I saw. I made Strombecker wooden model kits of both. Never saw a B-29 in my youth but there was a B-17 parked at KLGA.
Later, starting as a licensed mech in 1954 I thought Supper Connies and DC-6/7 were big. Never liked the look of the B-377 Stratocruiser but when working it I thought it was very big. Then the jets, first B.707, then DC-8 - wow. Then EAL leased three PAA B747 and they were mindblowing. Now I knew what big meant. And the tail engine on a DC-10, now I knew what High was.
On my first trips to Udva Hazy and Pima Air Museum I was amazed how small both the B-17 and the B-29 now looked. I had been spoiled.
The B-17 is almost a flying wing. The wing is a big proportion of the aircraft. The B-29 had a more elegant extended wing. And now, long retired, I see pictures of B-737 with insignificant wings stretched out (I managed two -200 models once) I assume are only needed to mount control surfaces.
I still vote for the B-17.