Ichigo Final Hollow Form or Naruto Sage of the six path's form

In the Human world Both Full Physical health

(and Naruto can fight against Ichigo's Spiritual form in this one off Battle)

Looking at Statistics of Attacks, Battle Experience and Things like Speed, Power

Both Prepared for a full blown Showdown

No interference from bystanders allies or rivals

Go

Seriously I think Ichigo would kick Naruto's arse he might Find The Nine tail's a nit tougher especially with Rasengan Planets But Ichigo's Gone through so many hard arse Battles and so has Naruto, it's more of who's Fighting harder to protect, this battle would have to have a Scenario like Ichigo is trying to defeat Sasuke and Naruto's trying to Protect him. Under these conditions Only then would Naruto and Ichigo go full out