I prefer Conan as he currently is over Shinichi on the start of the series. When the serie started he was just so arrogant. I don't hate Shinichi though.
I kinda think it was good for Shinichi becoming Conan. At the start of the series and when he was shrunk he was still the very much as his age-ego but with the time he stopped it and he became a more normal or at least more understandable character and actually emotional, thoughtful and profound person.
I think i would like him as much as Conan now if he was Shinichi again.