Berserk is unarguably the most popular seinen series in the world. It was created by Kentarou Miura, and currently, it is being worked on by Kouji Mori. The Berserk manga has over 300 chapters, which are filled with action, adventure, and an intriguing story.
It is one of the few unfortunate manga series to never receive a worthy anime adaptation. The 90s adaptation was great, but it pales in comparison to what the other anime series have produced. The newer anime adaptations used CGI to recreate the moments in the manga, but they flopped massively. Some fans have watched the anime because it's more convenient; however, there are still several arcs that have either been adapted partially or have no adaptation at all.
3 Fantasia Arc
It is the current story arc of the series, and it focuses on the aftermath of the Great Roar of the Astral World. Guts and his party continue on their journey to Skellig, but their journey is filled with all kinds of dangers, the biggest being the Sea God. The fight against the Sea God is incredible as Guts is pushed to the extreme. He is forced to use the Berserker Armor for an extended period, and it results in the armor almost devouring his consciousness. Luckily for Guts, the mysterious flame creature that he previously encountered helps him to recover a modicum of his consciousness. This creates a window of opportunity for Schierke to rescue Guts from the Berserker Armor.
Away from Guts and his party, Rickert slaps Griffith and immediately becomes a target for Rakshas. Due to this reason, he is forced to run away from Falconia. He is joined by Silat and Daiba on his journey. Back on the sea, the Black Swordsman party finally reaches Skellig after going through many ordeals. The main talking point from the arc is Casca's mind being restored. This was obviously a critical moment for her, as she had lost her ability to comprehend things after being abused by Griffith. For Guts, this meant that he could finally talk to the person that he holds so dear to his heart.
As the arc is still ongoing, it is difficult to put it above the two arcs as they have already been completed. However, it could easily overtake the Black Swordsman arc in the future if it continues down the same path.
2 Black Swordsman Arc
The Black Swordsman arc is the first arc in the manga, but it is set between the events of the Golden Age arc and the Conviction arc. The anime has adapted the Black Swordsman arc, although only partially, and sadly, the quality is not up to the mark. There are many notable things that have been excluded from the anime. So, it is better to read the Black Swordsman arc in the manga.
In this arc, Guts goes to the town of Koka, which is under the rule of an apostle known as Snake Lord. To send a message to the apostle, Guts starts killing thugs in a tavern, sparing one guy to deliver the message. By clearing out the thugs, Guts unknowingly makes a friend in Puck, an elf. Once the Snake Lord gets the message, he rides immediately to kill Guts, but he fails. In the Black Swordsman arc, Guts kills another apostle, who is called the Count. Guts somehow manages to beat the Count, who summons the God Hand as the final resort.
This is the first time the readers see Guts' archnemesis—Griffith or Femto. The Count refuses to sacrifice his daughter and ends up losing his soul. Guts escapes with his life and continues his journey. The arc gives the readers an insight into Guts' pain and how he keeps up a stoic demeanor despite suffering internally. All in all, it is a great way to start things off.
1 Millennium Falcon Arc
The Millennium Falcon arc is the fourth story arc, and it is set after the events of Griffith's incarnation. The 2016 Berserk anime has some material from the arc, but it did not adapt the arc completely. The Millennium Falcon is the longest arc in the series, and it was serialized from 2001 to 2010. In this arc, Guts comes face-to-face with Griffith. Enraged by the horrors that Griffith committed, Guts tries to attack him, only to be stopped by Zodd. The two clash for a while, but Griffith orders Zodd they have to leave. Before going away, Griffith makes it clear he is going to build his kingdom at all costs.
As the arc continues, Guts finally starts accepting people into his party. He is joined by the likes of Schierke, Farnese, Serpico, and Isidoro. The other notable events from the arc include Guts meeting Slan and obtaining the Berserker Armor. The Millennium Falcon arc also features Griffith's fierce battle with the Kushan Empire, which leads to its downfall and the birth of Falconia.
Overall, the Millennium Falcon arc is one of the best in the series. It has many notable battles, but above all, it has important development for Guts as a character. After the tragic events of the Eclipse, he had become a recluse, so accepting new people into his life was a big step for him. This was a sign that he was recovering from all the trauma.