I'm not including the DK and SD in the list, since not much of their capabilities are revealed yet (Except the DK)
10. Doll Gowther - Don't get me hated for this. I placed HIM here not only because he's part of the Seven Deadly Sins and the Ten Commandments, but his ability to manipulate minds makes him deadly. Who knows the extent of his power, but for now he'll be taking the 10th place.
9. Diane - There have been improvement in Diane's power, but that only happened once when they finished the trial gloxi and dolor offered. Not much of a big deal, since her power's only 30,000+. Compared to the current power levels of characters in the manga, it's almost too little. Her PL gets doubled if she performs dolor's dance, which enables her to exceed the power of one of the ten commandments. There might be character enhancement for her in the near future. But for now, I'll place her as the 9th on my list.
8. Archangels Tarmiel and Sariel - A.k.a. the "Dynamic Duo". As part of the Four Archangels and considered as Elites of the Goddess Clan, of course they are among the strongest characters. We all know how this two eliminated an entire legion of Demons in just a blink of an eye... The grace bestowed on them both may be enough to take down Chandler, as Sariel's Tornado will inflict lots of damage to the Demon. The power of the duo grants them the ability to make their own realm, which they name "The Realm of the Gods". We saw them both using this against Estarossa(Now Mael) when the commandments started defiling him, where they explained that "Nobody can survive in it, unless you surpass their combined might". They were both defeated later by Mael which is entirely sad (For me). I'm hoping the two to come back alive and aid the sins in some ways in the manga.
7. Chandler and Cusack - Teachers of Meliodas and Zeldoris, their power level that exceeds 180,000+ made them to this place. We all know the extent of their power, even Chandler alone can take out the entire sins(except Mel) alongside Gloxi and Dolor. They're masters and are greater versions of Mel and Zel, so... yeah.
6.1 Fairy King Harlequin - My boi. His improvement is so good that he was able to manipulate his spirit spear from afar. I dislike his new look though (Don't get mad at me.). King sprouting his fully-developed wings is of course a relief, look, he even managed to stand against Mael on himself where even Sariel, Tarmiel, and Derieri can't. His full power being exposed brought him to this place.
6.2 The Executioner Zeldoris - aka "The Prince of Darkness" and The Commandment of Piety (Formerly). He took against Escanor and Luedociel while Merlin was off fighting Cusack and Chandler. Zeldoris is a gifted child, like his brother, he's overwhelmingly strong, to the extent where he was proclaimed as one of the strongest sword wielders in the Demon World. He deserves this place. That's my boy!
5. Lion's Sin of Pride, Lord Escanor (THE ONE FORM) - All hail the Sun! Escanor at his "The One" form enables him to go whosyourdaddy and thereisnospoon (if you get my reference). At 12:00 PM, he turns to this form and becomes overwhelmingly strong, even stronger than Zeldoris, Chandler and Cusack or even Meliodas' Assault Form (For one minute, of course). By that, he earned the place of being the 5th strongest in the series as according to me.
4.1 Indura Forms - This involves Galand's acquaintance on his indura form, Derieri and Monspeet. We know how terribly strong these monsters are, to the extent where they can surpass even the Ten Commandments, and feared by the demons of the underworld.
4.2 Archangel Ludociel - Leader of the Four Archangels, having the grace of "Flash", this man is by far the most wicked Goddess in the series. Having a sadistic personality, he's very tricky. Look, he overwhelmed the Ten Commandments on their battle 3,000 years ago. He was then surpassed by Derieri and Monspeet on their indura form; At present, possessing the power level of 201,000, it means he's on a whole new level and is stronger than Cusack and Chandler. His grace also enables him to be fast, or even faster than light. But I kinda started liking him when he mention the sins to be his friends, and devoted himself to protecting them against the DK.
4.3 Daughter of Belialuin, Merlin - Boar's sin of Gluttony, Merlin, earns this position due to her magic power "Infinity". Enabling her to cast any magic anytime, also granting her wisdom on both Yin and Yang(lel), since she was blessed by the Supreme Deity and the Demon King. Merlin is intelligibly smart, tricky, and very clever.
3.1 Archangel Mael - Ludociel's younger brother, Mael is an Elite of the Goddess Clan and is also part of the Four Archangels. Being concluded as the strongest warrior of their clan, it's almost clear to imagine how strong he will be at his "The One" form. Since his grace got off by the time he turned into Estarossa 3,000 years ago by the Original Gowther, he got it back when Escanor offered him to take it. Mael was able to surpass even the second strongest ruler of the Underworld; The Sinner. Earning him this position.
3.2 The Sinner - The fusion form of Cusack and Chandler, each time he closes to his death, he becomes more and more stronger. Although the Archangel Ludociel was able to hold him back for a few minutes, he abruptly surpassed the archangel and got the sins alongside their allies into trouble. He lost great chances of winning when Mael arrived; When the Demon King came back possessing Meliodas' body, the sinner disappeared.
2. Ban - Fox's Sin of Greed, and part of the Seven Deadly Sins, his improvement made him so overpowered, that he was even able to withstand the Demon King's strength and power alone, where even the Archangels nor the rest of the Sins can't. The thousand years he spent on Purgatory served as his training on improving his power, and at present, he's facing off the DK himself and is almost on par of him.
1. Elizabeth and Meliodas - My favorite pair on the entire series, Meliodas being he Son of the Demon King and Elizabeth being the favored daughter of the Supreme Deity kinda reminds me of Romeo and Juliet(lmfao). Eli was pointed to be on par with the Archangel Ludociel's power level, or even stronger. She barely expresses her power since she loathe wars and stuffs. But the way how she b#tch-slapped Mel on his assault form and Estarossa may be hints to determine that she's strong. As for me, she's almost on par with Meliodas, being the Demon King's son and the Champion of the Demon World. Cursed by their parents, it's almost sad but nah.
This is my list according to my opinion.