Vinland Saga

Vinland Saga is a Historical, Epic, Adventure manga series written and illustrated by Makoto Yukimura and published by Kodansha, originally in their Weekly Shonen Magazine marketed towards teenage boys before being transferred to Monthly Afternoon aimed at Young-Adult men.

Plot
Set in the year 1013 A.D. in England, the series follows the young but skilled Viking Thorfinn, working with the mercenary Askeladd in a quest to kill the latter for the murder of his father.

Why it Rocks

 * 1) Insanely detailed artwork that's almost on the level of Berserk (ALMOST).
 * 2) A very interesting and realistic depiction of the Vikings around the 1000 A.D. years, with plenty of detail about specific events like the power clashes that happened around the time and so on, all depicted nearly beat for beat with some creative liberties taken, one with a lot of violence and moral ambiguity.
 * 3) A well written and intriguing story that pays homages to the aforementioned Berserk, like a young boy becoming a powerful warrior after being trained by mercenaries, but one that never rips off any part of it and instead puts in plenty of it's own original ideas. It also provides a deconstruction on the revenge genre, portraying it more realistically and having Thorfinn debate whether or not his quest for vengeance is really worth it, especially when he's forced to do some questionable things.
 * 4) Oddly enough, it's very loosely based on a true story as Thorfinn is a real Viking, though it changes up a lot of stuff as not much written history exists of the real Thorfinn. Askeladd, on the other hand, is entirely fictional, being named after a Norwegian folk character.
 * 5) No fantasy elements unlike Berserk, instead it's all realistic, with surprisingly realistic fight choreography that has very little embellishment.
 * 6) Gorgeously drawn scenes, especially battle scenes which have a ridiculous amount of detail in them.
 * 7) Many likeable and/or interesting characters
 * 8) Thorfinn is out for revenge, but has a moral compass unlike his other forced companions, and doesn't want to harm innocent people in order to achieve that goal and even tries to overcome his violent ways.
 * 9) Thorfinn's father, Thors, is a former member of the Jomsvikings who grew sick of the killing after his daughter, Ylvas, was born and tries to live a peaceful life while also purchasing a dying slave to make his final moments bearable.
 * 10) Thorfinn's older sister, Ylvas, is a hard working individual who becomes more so after their mother becomes sick and their father is murdered. At first as a way to cope with her grief from the latter, but later out of necessity for both her mother and her village.
 * 11) Askeladd, though he uses underhanded tactics in fights, is a man of his word, and always keeps his promises, even if he often puts loopholes in them. He even is content with fighting Thorfinn and takes that prospect more seriously than those under his command, but also has a sort of moral compass.
 * 12) Though not as gory as Berserk (but pretty close), the action is nonetheless hard-hitting and brutal, as well as highly realistic.
 * 13) The series even gets less violent as it goes along to focus more on character development to great effect.
 * 14) It had a crossover with Assassin's Creed: Valhalla.
 * 15) It spawned a fantastic anime adaptation.

Bad Qualities

 * 1) Some minor hiatuses, though these have excuses being that Yukimura couldn't keep up with a weekly schedule and preferred quality over quantity.
 * 2) Some mediocre villains, like Floki.