TOP 10 STRONGEST ARMAMENT HAKI USER

Armament or Busoshoku is a form of Haki that allows the user to use their spirit to create, in essence, an invisible armor around themselves. Notably, this form of Haki can be used to injure Logia Devil Fruit users. Similar to Tekkai, this Haki allows the user to defend against attacks that would otherwise cause them harm. Significant physical force can still overcome this defense. 

They also used to  harden parts of one's body, turning the area black, thus making the user denser and more formidable, and giving their attacks greater power. As demonstrated with Vergo and later Pica, it is possible for one to coat their entire body in Busoshoku Haki.

This is by far the strongest armament Haki user, the list will be updated from time to time.

10. TRAFALGAR LAW

Law is the user of Op-Op no Mi, devil fruit that allows its user to create a spherical space or "room", in which the user has complete control over the placement and orientation of the objects inside, making the user a Free Modification Human. Law used his Armament against doflamingo. Law also used his Haki against one of doflamingo top executives Vergo whose entire body covered in Haki. In battle between armament, the stronger armament will win. Law slashed through vergo armament Haki easily along with Island of Punk Hazard. 

9. RONOROA ZORO

Zoro is a character that possess great strength. This second strongest member in Strawhat Pirates learn Armament Haki from  Mihawk who trained him during time-skip. Black blade is the name of his sword after coated with Haki. Zoro did use armament haki against Pica, where he slashed through Pica's enormous body without any difficulty and defeated him.

8. DONQUIXOTE DOFLAMINGO

Doflamingo is a former shichibukai and also a celestial dragon. He used Busoshoku Haki in conjunction with his devil fruit ability to cut Smoker, a Logia Type user, seriously wounding him. He also toe-to-toe with luffy in terms of Haki clash before luffy went gear Fourth. 

Honorable Mentions

VERGO

Vergo is a former execitive of Donquixote Doflamingo family. He has a bamboo stick as a weapon of choice which he can coat with armament Haki. Vergo was also the first person in the series to use full body armament. Even doflamingo praised him for his Haki.

SAI

Sai is the 3rd division commander of Straw Hat grand Fleet. He used his Armament Haki against Funk Brother in the Colosseum. His Haki is as strong as Don Chinjao Drill and he even defeated Lao G

7. FUJITORA

Fujitora, is a Marine admiral. He was conscripted into the Marines through a World Military Draft during the two-year timeskip along with fellow newcomer Ryokugyu, both filling the two vacancies in the admiral positions caused by Kuzan leaving the Marines and Sakazuki becoming fleet admiral. Issho used his armament Haki against Sabo of the Revolutionary Army and also helped in stopping the Birdcage. Later Issho clashed against luffy and also stopped his attacks by coating his sword with armament haki.

6. MONKEY D LUFFY

Monkey D. Luffy is the captain of the Strawhat Pirates and is one of the members of the Worst Generations. He possesses a bounty of 500,00,000 berries and considered as the one of the member of worst generation pirates. Luffy learned his Haki from Rayleigh during time-skip. His Bushoshoku haki is used in most of his attacks such as Red Hawk, Kong Gun, Grizzly Magnum and many more. Luffy armament become twice as strong when he is in Gear Fourth state. His defenses becomes extremely powerful with the combination of elasticity and armament on certain part of his body. Not even doflamingo awakened Devil Fruit are able to do damage against Luffy when he is in Gear Fourth. 

5. CHARLOTTE CRACKER

Charlotte Cracker is the member of the Big Mom Pirates and is one of the three Sweet Commanders of Big Mom Pirates. Cracker is the user of  Bisu Bisu no Mi is a Paramecia-type Devil Fruit that allows the user to generate and manipulate biscuits at will, making them a Biscuit Human. Cracker has incredible mastery of Busoshoku Haki, which he uses to harden his sword and biscuit armor. 

Luffy, a highly proficient expert of Busoshoku Haki himself, described Cracker's Busoshoku Haki as extremely tough, which can easily withstand Luffy's Haki enhanced strikes. After imbuing his sword with Haki, Cracker was able to cut Luffy's arm while he was fighting in Gear Fourth, further demonstrating the power of his Haki

4. CHARLOTTE KATAKURI

Charlotte Katakuri is the member of the Big Mom Pirates and is one of the three Sweet Commanders of Big Mom Pirates. Katakuri have the highest bounty shown in the series so far which is amounted to 1,057,000,000 berries. Katakuri is a user of Katakuri ate the Mochi Mochi no Mi, a special Paramecia-type Devil Fruit that lets him create, control, and transform into mochi at will. His mochi is extremely thick and adhesive, allowing him to trap even extremely strong enemies with it. 

He frequently uses these abilities in hand-to-hand combat, sprouting several tendrils of mochi on his body to act as extra fists or legs; he can imbue these tendrils with Haki to deliver hard punches and kick. Katakuri is also extremely skilled at using Busoshoku Haki, as shown when he imbued his mochi leg with it in order to bludgeon and injure Luffy. He can also harden his arm, as shown when he countered Luffy's attack.His Haki enhanced strikes are powerful enough to counter and overpower Luffy's own Haki enhanced attacks,and he has stated that his Busoshoku Haki is superior to Luffy's.

3. CHARLOTTE LINLIN, BIG MOM

Big Mom is one of the Yonkō and is the captain of the Big Mom Pirates. She is the queen of the Totto Land and is the strongest female character in One Piece right now. Big Mom has immense superhuman physical strength, demonstrated by her ability to climb tall buildings despite her massive size, throw punches with tremendous destructive power, and hurl Prometheus with extreme force using only a single arm. Big Mom has immense mastery of Busoshoku Haki. By hardening her arm, she could easily block Luffy's Gear Fourth Kong Gun, a tremendous feat as Luffy's Kong Gun is powerful enough to break through powerful Haki based defenses of highly skilled Busoshoku Haki users such as Doflamingo, Cracker and Katakuri. Like Luffy's Gear Fourth, her Busoshoku sports flame marks at its ending.

2. SABO, REVOLUTIONARY ARMY

Sabo is a member of the Revolutionary Army and is the second in command of the Revolutionary Army. He was first presumed dead but was later revealed that he was alive. During those years Sabo trained about became one of the strongest members of the Revolutionary Army.  Sabo has shown incredible mastery of Busoshoku Haki, which he can imbue into his arm or his pipe.  His Busoshoku Haki is strong enough to shatter Burgess's Haki infused right arm armor, as well as Diamante's sword. His mastery of Busoushoku Haki is superior to Bastille's, as seen when the Vice Admiral attempted to cut him down with Haki enhanced sword strikes; not only did Sabo manage to block his Same-kiri Bocho, he even managed to destroy the entire blade with relative ease. Sabo also able to destroy an entire colliseum with his Dragon Claw. 

1. MONKEY D GARP

Monkey D. Garp is the former Vice Admiral of the Marines and then he became a training officer in the Marines.  He demonstrates extremely proficient skill in Busoshoku Haki, being able to injure Luffy several times, bypassing his rubber body. He could harden his fist and turned it obsidian black, allowing him to counter and even crush Chinjao's Haki-enhanced drill shaped head 30 years ago, proving his superior mastery compared to Chinjao, who himself is a powerful expert Busoushoku Haki user in his own right. During the Battle of Marineford, he managed to punch and hurt Marco despite the latter being in his regenerative phoenix form.

thats it from me.