Well, lower-level Naruto could probably whoop lower-level Aang. That is, if Aang would stay still and let Naruto land a blow.
Though, upper-level Aang against Naruto? That is a close call. With his capability to manipulate the four elements, and various extensions of those elements, not to mention, the Avatar State, which is basically a psychic elemental berserker rage...
I don't know much about Naruto, other than that he has amazing mastery of chi. That could put him make him an excellent match for Aang's powers, even potential to outdo him.
The only thing that brings the match-up into question, is the extent of Aang's Energy Bending. It can pass on knowledge, and manipulate people's access to chi (in practice, it's been used to bestow or take away elemental bending powers, but I'm pretty sure it would effect ninja powers, because they're based on chi, too). Energy Bending, combined with his natural agility gained from Airbending, and potentially chi-blocking learned from Ty Lee after she turned good--even Bloodbending, if he thought it was absolutely necessary...I think fully-realized Aang could pose a real threat to Naruto.
He might even be able ruin Naruto's connection to the Nine-Tailed Fox, if given sufficient time to develop his powers.
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)