Same here, having seen 594, 604, 609, and 612, I think 604nm is pretty much pure orange :beer: 594 has a gold yellow color, 612nm has a hint of red, 609 is pretty similar to 612, slightly more orange but still detectable hints of red
Something that is by definition a range of values, has no singular state of purity at any individual value. Every wavelength in your poll (except 585) is "pure orange" because every value is entirely within the definition of orange, and is not to any degree outside of the definition of orange.
There is no singular answer. If you had asked "what wavelength of orange do you like best?", subjective answers of individual wavelengths would be fine.