Onepiece is such an awesome series and better than Naruto for the most part but I prefer Naruto Over Onepiece for reasons:
1. Naruto was one of the first Anime that really impacted my life, looking back brings back nice Nostalgia and gives me some Inspiration
2. I enjoyed Anime more than the Manga. The Anime brings nice Addition to the story always want more expansion the world building and more Character Developments. It also gives nice in depth feels with the soundtrack. Some fillers brings justice to some certain Arc such as Fourth Great Ninja War.
3. I have some passion with the characters more than other series mostly are my favorite, they're appealing and interesting characters.. Most recently, Hinata plead Neji to save Naruto so I'm overhyped! Cause Neji is my Favorite
4. The series is always too entertaining whether I liked it or not, even despite the War Arc is lame . Even I rant too much how it gotten worse, I always thinking about the series and I always have Hope that it'll get eventually better. Where Onepiece, the slow pacing really dragged too long, it gets hella boring like fisherman Island arc
Lately Naruto is been doing well, so I can't wait for both the Manga and the Anime!