Kabuto's best reaction feat is evading susano arrow from close range while SM Naruto's best feat is evading AyIII's hell stab at the last moment and reflecting his arm but to be more detailed it was Naruto's clone, using SM, who achieved this feat. the Real Naruto, while using SM, should have better than that. I would say it is close though i would go kabuto. Both have very little shunshin feats to really say who has better shunshin.
KCM Naruto's best reactions feat are physically reacting to v1 Ay by just blocking his punch and mentally reacting to V2 Ay by shunshin'ing away. I personally think he is below both SM Naruto and SM kabuto in terms of reactions but far above in terms of shunshin speed.