Nearly 40 years ago I was taking a course in fracture mechanics, taught by a metallurgist ex-Lockheed Skunk Works. I asked him that question, but with safety in mind as at the time I was a very nervous flier. His answer was the Convair 880/990 (remember, this was 40 years ago). I asked, "What about Boeings?" He said there was no elegance in their designs - they got burned in the past designing too close to the limits so they overdesign everything. To somebody who came to class every day with failed airplane parts explaining how when the engineer screwed up this design, this part broke and xxx people died, this made me a lot more comfortable when flying any of their planes. Wouldn't you know the Turkish Airlines DC-10 crashed during the semester I was taking this class. The instructor came to class carrying a DC-10 cargo door latch and gave us a lecture on PPD (piss poor design). Of course we know now it was not a metallurgical failure but it certainly was classic PPD.