I was surprised that your list of greatest airplanes didn’t include the longest lived military planes in the U.S. inventory. I refer to the C-130 and B-52. I guess the reason is your readers are general aviation folks and they have not had much exposure to these two incredible airplanes. The C-130 has indeed seen some general aviation use, but the B-52 has only been used by the USAF.
Both the C-130 and B-52 have been in constant service since the 1950s (I think) and are still front line active aircraft. While there are many newer models of both cargo and bomber aircraft in the military inventory, most of the “replacements” for these two airplanes have gone to the scrap yards. There is no plan (that I know of) to stop using either of these planes for the foreseeable future.