Warning, this post may contain spoilers. So if you are not at episode 200 or so of one piece, you may be spoiled. That said, let me let tell you my favorite one piece arc so far.
So I'm not the most "up to date" one piece fan there is. I'm only on like episode 250 and I haven't seen every episode up till then, like I'm missing about 100 episodes. Yeah I'm bad at watching the series. 4kids ruined the first 100 episodes for me, and it's hard for me to watch pre-funimation episodes. Anyways, enough of my being a bad fan. Time for my favorite one piece arc.
Now so far my favorite arc is the Marine base filler arc that takes place after Skypea. So what makes this arc so cool for me? It's quite simple, it explores an enemy that we don't see very often and the enemy is very different than the normal enemy.
So what do I mean by "don't see very often" and "very different than normal enemies." Well lets explore the "don't see very often" aspect first. From what I remember, the Marines (or if you're watching 4kids or subbed, Navy) is not faught very often. They are the law men of the world, and they fight pirates. Well, most of the time, the marines aren't really fought by the straw hat pirates and only serve as a reason for them to get out of the city and move on to the next. Sure, watching the straw hats constantly fight law enforcement would be a little repetitive, but come on, these guys are super strong and can take on any pirate or dictator or whatever they encounter. Why are they so afraid of the Marines? Well that leads us into my second point.
So what makes them so different from normal enemies? Well in all the fights I've seen so far, basically it's Lufy and the rest of the straw hats fighting an army of weak henchmen that go down in one hit as they make their way to the head enemy. Then when they reach the enemy, the enemy is crazy over powered and it's a big fight scene against Lufy against the head enemy while the rest of the crew fight the other over powered big enemies. That's cool and all, but that's kind of reparative.
Now the Marine arc is really different than the rest of the enemies. First, they're fighting the one enemy that they actually fear. Second, it's not the normal "we need to fight and defeat these guys," it's an escape arc. Third and most important, the Marines aren't the normal "army of weak henchmen leading up to the big boss fight" type of enemy. The Marines are strong. They have good weapons. They are strong, but not over powered. But what they lack in overpoweredness, they more than make up for with numbers. They are maybe twice the size of the normal army of weak henchmen. This makes for a great fight. This time around, it's the straw hats fighting off an army of competent enemies that just don't go down.
So review time of why I like this so much. First, it's an escape story, not the normal "we need to beat these guys and rescue this city." Second, it explores an enemy that we don't know much about except that it's the only enemy that the straw hats actually don't blindly fight and avoid fighting them at all costs. Third, and most important, they're fighting enemies that aren't complete wimps or overpowered.
Well I hope you enjoyed my rambling. This has been pokematic signing off and bu-bye.