Bushido has advantages outside of parry--most importantly, perfection and confidence. Plus, you suffer a penalty for holding a shield with a throwing weapon, which precludes the choice of parry. Although the devs say that this penalty is mitigated by the parry skill, my experience tells me differently. If you're forced to chose between parry and bushido, I'd go with bushido.
Keep in mind that this is just one guy's opinion.