The biggest barrier for new fans is the name change. In the Funimation dub, hearing "Conan" ask "Rachel" to call him "Jimmy" feels jarring if you know the source material. However, for pure nostalgia-driven viewers, "Richard Moore" is as iconic as "Kogoro Mouri."
Conclusion The “best” Detective Conan dub depends on priorities: modern Funimation dubs generally offer higher production quality and more faithful localization compared with early heavily edited versions, but no English dub fully replaces the original Japanese with subtitles for accuracy and completeness. Fans seeking both accessibility and preservation of mystery elements should prefer the more recent official dubs when available and rely on subtitles for core story arcs.