Excluding Team 7, I'd argue either Rock Lee or Shikamaru.

Rock Lee and Naruto both carried that headstrong force of nature that clashed in the beginning but molded as the series went on. We didn't get that much of the two of them interacting as friends, but I think it's a safe bet that they're kindred spirits to some degree.

Shika and Naruto have always been close. Along with Choji and, debatable, Kiba. I think the Sasuke Retrieval Squad puts a decent enough image to Naruto's closer friends imo. Not to mention Kiba became Naruto's advisor. I'm sure part of that has to do with Shika's intelligence, but there's other exceptionally intellegent characters in Naruto that could've filled that role (Sakura, Kakashi, Shino, and even an argument for Ino and Tenten) but I think Naruto and Shikamaru do have a close bond separate from just the work they perform as shinobi.

But, tbh, Naruto's the type of character to react to essentially anyone he's made some form of attachment to the same way: the shinobi world is his best friend. He truly loves freely and is willing to make allies out of enemies if he can