Ive tried several FitBit to Apple Health sync applications and this one is currently the best. It is accurate, it handles date transitions properly - especially around the beginning of log data - many other apps dont handle this and can result in years of data carried backwards. It is extremely quick to sync. It syncs more categories than a lot of the other applications. But, above all, the developer is extremely responsive and thoughtful towards bug submissions and feature requests.
Da5is about Health Sync for Fitbit