I can understand why people who've read the 1963 version of Princess Knight don't like Franz very much, but looking into the original 1953 version it feels as though the revised version just failed to do him any justice, even after giving him an older brother to worry about (and then deciding to not do anything with it).
I don't know if it was because of the inclusion of newer and more updated characters who got more focus or a lack of planning, but they really did Sapphire and Franz's relationship dirty in the 1963 version.
In the 1953 version, they actually interact with one another, try to one up each other, hang out, go on a mission to save Sapphire's mother, etc. This is what I wanted to see in the 63 version!
I'll admit some stuff in the 53 version is probably a bit "meh" compared to the 63 version, but at least we got good romantic chemistry of it. And that is not something I get to say when referring to Osamu Tezuka's mangas!