In the Naruto series, the titular character had a fierce rivalry with Sasuke Uchiha, and in the first major story arc, this rivalry pushed both Naruto and Sasuke to new heights. After Sasuke finally left the team, Naruto needed a new rival. But who should it be?
If Naruto could, he might even choose a character from another shonen series as his rival, and start competing with him or her to push himself to new heights. Ideally, Naruto's new rival will be someone who has an upbeat, competitive attitude, and the stubborn will to persist despite all odds. Within his own universe and beyond, Naruto has quite a few choices for his new best rival.
10 Benimaru, The Ogre Swordsman (That Time I Got Reincarnated As A Slime)
At first, Benimaru the ogre was driven by rage and retribution since he lost his entire village to orcs and their masked leader. But once he made peace with Rimuru Tempest, Benimaru became a finely-honed instrument in battle, driven by loyalty and discipline rather than anger or grief.
Benimaru pushes himself hard to defend Rimuru's new kingdom, and he has a strong sense of sportsmanship and honor in battle. He would certainly approve of Naruto, and the two of them could compete to see who can truly be the strongest.
9 Killer Bee, A Fellow Jinchuriki (Naruto)
Naruto fought his fellow jinchuruki, Gaara of the Sand, after the Chunin Exam arc ended, and the two jinchuriki did not get along until later. However, Naruto later met another jinchuriki, the eccentric Killer Bee, and became his ally. Over time, Killer Bee learned to respect Naruto a great deal. He admired Naruto personally, too.
If Naruto and Killer Bee had met sooner, they could have formed a high-voltage rivalry as fellow tailed-beast users, and this definitely would have inspired Naruto to tame and use the nine-tailed fox's power sooner. If Killer Bee can master his tailed beast, then surely Naruto can do the same to his own.
8 Ikkaku Madareme, Who Aspires To Surpass Kenpachi (Bleach)
Naruto would be a bit off-put by Ikkaku Madarame's punkish attitude at first, but Naruto has dealt with rougher people than this before. And besides, Ikkaku has a sense of honor that Naruto would definitely find appealing. Ikkaku is tough, but he means well, and he never gives up.
Ikkaku is stubbornly determined to become the strongest swordsman of all, and he longs to eclipse his mentor and personal hero, Captain Kenpachi Zaraki. Naruto would learn a lot by sparring with the ferocious and skilled Ikkaku, and they can relate to each other's dreams and goals easily. Naruto would also become Ikkaku's new drinking buddy, replacing Tetesuzaemon Iba of squad 7.
7 Avatar Korra, The Strong-Willed Waterbender Hero (The Legend Of Korra)
Avatar Korra has a lot in common with Naruto. Both of them are stubborn, hard-headed heroes who inspire and exasperate their teachers in equal measure, and they both feel frustrated by growing up in obscurity (Korra was confined to the remote South Pole for a long time).
Further, both characters possess a mega-powerful being inside, with Korra having the great light spirit Raava in her while Naruto, naturally, has the nine-tailed fox's spirit. Both characters would be delighted to make friends with each other and compete in their training sessions all day long. That would definitely cheer them up, especially Naruto.
6 Izuku Midoriya, All Might's Successor (My Hero Academia)
It's true that Izuku Midoriya and Naruto Uzumaki are both shonen protagonists, but that is not the only reason why these two characters should meet. Izuku grew up in obscurity, just like Naruto and Avatar Korra, and he is determined to make up for lost time. He must become an inspiring hero, no matter what.
This is similar to Naruto's quest to become Hokage, and like Naruto, Izuku started off with very little except a dream and sheer willpower. He then gained One For All, and with such power, he could easily spar with Naruto and challenge him on the training field. Naruto would never pass up an opportunity like this one.
5 Joseph Joestar, The Hamon Expert (JoJo's Bizarre Adventure)
Joseph Joestar was the hero of the Battle Tendency story arc, and he was an even better shonen lead than his grandfather Jonathan Joestar was. Joseph is tough, cool, brave, and noble, and he had a fierce rivalry of his own, often clashing with Caesar Zeppeli during their joint training arc.
For that reason, Joseph would make a great rival to most other shonen leads, and that definitely includes Naruto Uzumaki. In particular, the two of them are fun-loving pranksters, and they would get along great on the training field and in everyday life.
4 Monkey D. Luffy, The Rubbery Ship Captain (One Piece)
Once again, the best rival for a shonen lead is another shonen lead, and in this case, Monkey D. Luffy would be delighted to compete with Naruto Uzumaki to see who's really top dog of these high seas. They are both nobodies who aspire to reach the top of their respective worlds, Hokage vs pirate king.
Luffy is a stubborn and good-natured fellow just like Naruto, and he and Naruto also share a great fondness for food. After a hard day of sparring and training together, both boys could fuel up with either grilled meat or hot ramen and look forward to the next training session.
3 Inosuke Hashibira, The Wild Demon Hunter (Demon Slayer)
It's true that many of the most ideal rivals for Naruto have a similar personality as him. But sometimes, it helps to have a wild, aggressive rival who can teach the other rival how to stay on their toes and maintain a sharp, competitive edge. That's where Inosuke Hashibira comes in.
Naruto would have a lot of fun with a friendly rival, such as Luffy or Korra, but once in a while, he needs someone feral like Inosuke to keep him on his toes, sharpen his instincts, and keep him primed for combat at any time. It may be annoying at first, but this could pay off in the long run.
2 Natsu Dragneel, The Fire Dragon Slayer (Fairy Tail)
Once Naruto is done training with Inosuke, he can move on to another shonen lead who is fairly similar to him: Natsu Dragneel, of the Fairy Tail guild. Natsu is hotheaded and competitive, as one might expect, but he does cherish his friends and allies. He'd risk his very life for them (and has).
On a personal level, Natsu and Naruto would get along just fine, and they are roughly equal in firepower in combat, so their training sessions together would be stubborn and exciting affairs. Natsu has never seen shadow clones before, but he will now, and what an exciting challenge they will be.
1 Maki Oze, The Fire Soldier (Fire Force)
While characters such as Luffy, Inosuke, and Korra fight mostly on instinct, Maki Oze the fire soldier operates differently. She has a military background, and Maki combines military discipline with astonishing pyrokinetic powers. She can beat any recruit into fighting shape with ease.
Maki has a good heart and a tough exterior, making her the ideal sparring partner for Natsu and a worthwhile rival. Naruto may have more raw strength with his fox chakra, but Maki boasts superior discipline, experience, and expertise, and Naruto would do well to follow her example. He could learn a lot from this rivalry.