One Piece entered a two-year time-skip after the major events of the Paramount War finally wrapped up. During this time-skip, the Straw Hat Pirates trained their skills to be better equipped for the New World and the strong enemies that they would encounter along the way.
After the time-skip, the Straw Hat Pirates met on Sabaody Archipelago. Finally, they continued their adventure across the Grand Line, intending to reach the Final Island, Laugh Tale. So far, they haven't yet visited as many places as they did before the time-skip. However, every arc after the time-skip has been nothing short of phenomenal.
7 Punk Hazard Arc
The very first island that the Straw Hat Pirates visited in the New World was Punk Hazard. Although they didn't intend to go to the island, the crew ended up there and found out about Caesar Clown's experiments. Luffy met Trafalgar Law once again, and thus an alliance to take down Kaido began.
Furthermore, Doflamingo was introduced as an obstacle that they had to get past while also setting up the Four Emperors Saga as a whole. This arc put Luffy's new abilities to the test against Caesar's likes, a Logia user, and further solidified his goal of taking down all the Four Emperors. It also gave the fans a lot of lore about dragons, introduced Momonosuke and Kin'emon, along with lots of information on Vegapunk and the fight between Akainu and Aokiji.
6 Zou Arc
Another masterfully written arc, Zou, is one of the shortest ones by Eiichiro Oda so far. After the events of Dressrosa, the Straw Hat Pirates reach Zou with a Vivre Card. The first group to arrive there is met with the place in ruins, and the land of Minks is revealed to have been destroyed by Jack the Drought. After taking care of everyone, the Big Mom Pirates take Sanji for his shocking marriage to Big Mom's daughter, Pudding.
Later, Luffy's group arrives on Zou and knows what the Road Poneglyphs are all about. The road to Laugh Tale becomes clearer, and most importantly, the truth about Kozuki Momonosuke and Oden is revealed. This arc also sees the formation of the Ninja-Pirate-Mink-Samurai alliance and, finally, sets up the Whole Cake Island and Wano Country arcs' events.
5 Dressrosa Arc
Dressrosa is the arc that precedes Zou, and it focuses primarily on Donquixote Doflamingo, one of the Shichibukai. This arc sees Luffy and Law take down Doflamingo and also ruin Kaido's SMILE business while they're at it.
Sabo marks his return to the story in this arc, and the Navy Admiral Fujitora is also introduced. In his fight against Doflamingo, Luffy finally goes all-out and unleashes Gear Fourth to overcome him and free Dressrosa from his shackles, and most importantly, the Straw Hat Grand Fleet is finally formed.
4 Reverie Arc
One of the most content-heavy arcs in One Piece, Reverie spans over just a couple of chapters; however, it is still considered one of the very best in the series. The biggest event to take place in the arc is the dissolution of the Shichibukai system. However, even bigger reveals are made in the following chapters. The existence of a giant Straw Hat at Mariejois is revealed to the fans, and Imu is introduced as the man on top of everything in the One Piece world.
Furthermore, the Revolutionary Army declares war on the Celestial Dragons. If all that wasn't enough, Shanks makes an appearance in front of the Gorosei, telling them about a certain pirate, while Luffy is declared the Fifth Emperor of the Sea.
3 Fishman Island Arc
Fishman Island is a phenomenally written arc that is often given far less credit than it deserves. It encapsulates the adventure aspect of One Piece perfectly. Lying 10,000 meters below the sea level right under the Red Line, the Straw Hat Pirates go there to get to the New World. While this arc didn't have any powerful antagonists, it did have one of the evilest ones in Hody Jones, who just the personification of hatred towards a race without reason.
The arc also gave fans a glimpse of what the Straw Hats had learned during the time-skip and set up Jinbe becoming a Straw Hat. What's more, it gave a deeper insight into the human-Fishman relationship, revealed that Shirahoshi was indeed Poseidon, and introduced the fans to Joy Boy and Noah.
2 Whole Cake Island Arc
Quite easily one of Oda's very best arcs in One Piece, Whole Cake Island, sees Luffy travel to Totland to rescue Sanji from Big Mom's clutches. Forced to leave the crew, Sanji ends up fighting Luffy; however, not long after, he can't help but seek help from him. The arc only gets better as the Straw Hat Pirates ally with the Firetank Pirates and attempt to assassinate Big Mom.
Sanji's past is revealed to the fans, and the evil Germa is eventually rescued by the son Judge hated. One of the biggest fights in the story, Luffy vs. Katakuri, takes place in the Mirror World while Sanji bakes a cake to save everyone from Big Mom's rage. To protect Luffy, Jinbe, Germa, and the Fishmen stay behind to stop Big Mom as the Straw Hats leave the Yonko territory.
1 Wano Country Arc
The Wano Country arc is quite easily the best in post-time skip One Piece and possibly even the entirety of the story, even though it's not over yet. The arc sees the Straw Hat Pirates reach Wano Country and take on two Yonko of the Sea, Kaido and Big Mom. Wano Country's horrible past is revealed to the fans as Kin'emon declares to have come from 20 years in the past to avenge Oden.
As the arc progresses, Luffy also trains his Haki after getting defeated by Kaido once, and most importantly, fans get a masterful flashback of Kozuki Oden and his entire life. Following that, the Onigashima Raid begins, and Luffy takes his first step towards becoming a Great Pirate by attempting to vanquish Yonko Kaido.