He is undoubtedly the strongest along with Sasuke that is what Kishimoto said......In Boruto movie though when Mitsuki was telling about what his parents thought about Sasuke he made it sound like Naruto> Sasuke...but in both Gaiden and Boruto movie he has been heavily nerfed. The author put him in the role of defense rather than him being the front line assaulter he usually is. The size of the bijudama he tanked in Boruto movie actually showed his strength...He was able to contain the explosion on his own and protect the village from major harm from a bijudama of that scale. No one including Sasuke could have done that, apart from Minato who obviously could have teleported it somewhere else. There are still debates if he still has RSM...well no reason for him not to have it but it is a fact that if Naruto showed his true powers everytime there was a calamity without being nerfed the new characters specially Boruto will never be able to come out of his shadow