Okay, I'm probably the weird one here, but I don't really go for those huge, novel-length 'growth' epics everyone recommends. The stories that actually stuck with me were the small, weird ones. There's this one shot where Naruto accidentally swaps bodies with Kiba after a failed jutsu, and the whole thing is just them figuring out how to navigate each other's lives for a day—Kiba having to deal with Naruto's chakra control, Naruto experiencing the world through heightened senses. It's not grand, but the subtle understanding they develop feels more genuine than any 'power-up' arc. I find a lot of those massive fics get so bogged down in training montages that the actual relationship gets lost in the noise.
I'd say check the 'G' and 'T' rated ones on AO3, sort by kudos, and then skip anything over 100k words. The sweet spot is usually between 20k and組織 60k. 'Outrunning the Fox' had its moments, but honestly, I dropped it after the third chunin exam rehash. Sometimes growth is just two idiots realizing they're not so different, not saving the world again.