Senju, they're stronger in any way save sealing jutsu.
Uzumaki because Naruto has Six Paths Chakra mode, and Nagato is weaker only from Hashirama (from members of Senju clan). Only Naruto can wins.
canonically the senju is the strongest clan overall, sure Naruto and Sasuke as they are now are arguably stronger than any member of the senju, but overall, taking all members of the Uzumaki except Naruto and Nagato into account Uzumaki is at best on par with hyuga and far beneath Uchiha and Senju.
They're of the same lineage with extraordinary life force, vitality and longetivity.
So it would come down to their skill set, uzumakis' deal more in fuinjutsu and Senju more offensive with all ninja skills, so i would give it to senju clan based on that advantage bbut that doesn't mean the uzumaki don't have scary offensive fuinjutsu.
Hell they were destroyed because of it and EVERY uzumaki fuinjutsu show are undeniably badass
Personally, i copnsider it a travesty that we didn't get to see both clans skill in detail like the uchiha, smh lol
If bolt is parallel to his naruto with his looks, his combat style may be similar to sasuke just like gohan was to piccolo
I feel bolt's design was influenced by Gohan's since Kishi-sensei is influenced by Dragon ball a lot