Well, certainly the characters suffered to varying degrees, but Ginny’s possession was significantly more dramatic. I found it strange since emotionally, Ron was probably at least as close to Harry as Ginny was to Riddle’s diary. Perhaps the answer is that Harry also had a “non-horcrux” component to him, while the diary was entirely a horcrux, with very little characteristic otherwise. Dumbledore mentions, when discussing Nagini, that it is unwise to use a living creature as a horcrux, since the living creature also has free will, which presumably interfers with horcrux function. I guess Harry’s free will overcame his horcruxian (?) tendencies?
Part of it could be the different things used as horcruxes. The diary, being a clear recording of Voldy’s thoughts, was pretty well suited to channeling him even before resurrecting him. The scar in Harry, a Voldy didn’t even try to make, was so much. And there’s still the problem of Ginny double dipping the horcruxes. But I still think there was plenty of badness to go around for Harry’s horcrux, he’s a serious bad luck magnet.