Without her last-ditch efforts, Tanjiro would have remained a demon and could have caused a ton of problems to the demon hunters around him. Despite all of these, Sanemi's raw power and speed are far higher compared to hers, which means that he can beat her with ease.
Sanemi's Wind-Breathing Is Too Similar To Akaza's Blood Demon Art. Although Sanemi Shinazugawa is arguably stronger than Iguro, he would've been a bad matchup against Akaza.
Tanjiro Kamado
In terms of achievements, Tanjiro outsmarted Water Hashira with just his natural instincts and defeated a bunch of demons even before becoming a member of the Demon Slayer Corps.
6 Can't Defeat: Giyu Tomioka
If Tanjiro is unfortunate enough to find himself on the wrong side of Giyu's sword, there's no way Tanjiro is winning that fight.
In his own franchise, Tanjiro is outclassed by most of the nine Hashira as of the end of season 1, including Giyu Tomioka. It's easy to compare Tanjiro's strength to Giyu's — since they are both demon slayers — and they even use the same element: water.
Sanemi, probably. Obviously Sanemi. Unmarked Giyu did better against Akaza than Marked Tanjiro did (without Transparent World or Selfess State yet). Considering Unmarked Sanemi is on par with Unmarked Giyu, Unmarked Sanemi would definitely win against Marked Tanjiro.
But if we are talking about the human form, then it's a big fat NO, because Tanjiro has just mastered the Sun Breathing whereas Yoriichi is the inventor of it, also he's way more powerful and holds an unfathomable battle intellect, larger than any Demon Slayer in history, so in conclusion, no one is remotely close to ...
This eventually helped Inosuke and Kanao to defeat him. However, Doma in his strongest form, may be able to beat Sanemi using his Blood Demon Art. By employing this, he can create a fine powder of ice crystals that is toxic if inhaled.
While Sanemi and Giyu are pretty evenly matched, it's possible Sanemi would win a fight between them based on his ruthless nature alone. Giyu has shown mercy, but Sanemi isn't the type to hold back for any reason.
Giyu Tomioka Fulfilled His Promise to Protect Tanjiro
The Water Hashira, Giyu, survived the "Infinity Castle" arc after fighting beside Tanjiro against Akaza and Muzan. Though his sword was snapped by Akaza, and he lost an arm to Muzan, Giyu fought with Tanjiro and his fellow Hashira with everything he had.
Tengen Uzui
He is the fastest Hashira, and the second physically strongest. Obviously, then, Tengen Uzui is rather proud. He is demanding, fussy, boastful, and prone to selfishness. But he is also ultimately kind and caring, with great love for his three wives as well as the other Hashira.
While Muichiro is certainly talented and worthy of praise, the Mist Breathing Style leaves something to be desired especially compared to the Hinokami Kagura. Comparing an end-of-story Tanjiro to an end-of-story Muichiro, Tanjiro likely takes the win home 99 times out of 100.
As a result, Tengen Uzui has to deal with the moniker of being the least powerful Hashira around. Of course, that's not the worst thing in the world, as all Hashira are strong. He's still incredibly powerful and can give any demon a run for their money.
Sanemi's sheer power and speed will be able to overwhelm Nezuko even in her final form. Nezuko's Blood Demon Art would not work against Sanemi since he's a human, and he has the ability to decapitate her head if he wanted to.
1. Gyomei Himejima. Gyomei Himejima, the Stone Hashira, is the strongest Hashira in the Demon Slayer corps in terms of strength and swordsmanship. He is the only person who uses spiked flails and an axe instead of standard swords to kill demons.
Sanemi was able to launch his Seventh Form: Gale, Sudden Gusts onto Muzan, but he couldn't keep up with him because of the difference in strength.
7 Can't Beat: Giyu
Giyu is one of the legendary Hashira, and he's brought down demons far more powerful than Nezuko. With his level of skill and impressive agility, he'd easily defeat Tanjiro's little sister. In fact, when Giyu first meets Tanjiro and Nezuko, he almost does kill the latter.
Despite being the lowest of the Upper Ranks, Gyutaro showed much of his demonic prowess by making Tengen lose his left arm and his left eye in battle. However, Giyu would have been a better opponent for the demon and could have defeated him without losing any limbs.
Master Swordsman
He has repeatedly demonstrated his extraordinary combat skills and proficiency. Sanemi is one of the most powerful and skilled swordsmen in the Demon Slayer Corps; even Upper Rank 1 Kokushibo was impressed by Sanemi's skills and refined sword techniques.
Nezuko Kamado
When they first met, Sanemi had a deep hatred for demons.
Overall Abilities: As a Hashira of the Demon Slayer Corps, Sanemi is a very powerful and skilled combatant.
2) Tanjiro Kamado
With his awakened Demon Slayer Mark along with his Transparent World, he could match up with Kokushibo's speed. Moreover, Tanjiro's Sun Breathing is too lethal for Kokushibo and with his swordsmanship he can rival the latter.
Yoriichi would be able to defeat every single Hashira on this list without breaking a sweat. Such was his reputation and skill in swordsmanship.
The aforementioned Hashiras are leagues above Tanjiro and they were easily overwhelmed by Kibutsuji Muzan's strength. One of Tanjiro's biggest strengths is that he can use the Breath of the Sun, but Tanjiro alone cannot kill Muzan given the Demon King's ridiculous rate of regeneration and raw strength.
As the battle reached its climax, Tanjiro was able to knock the doll's head off and discovered that the mechanical body contained a mysterious sword. Fans of the manga will recognize this sword as the one carried by Yoriichi Tsugikuni himself.