If it goes down to choosing, I always prefer long series. The longer time I invested that richer the reading experience to me! (And I’m pretty good on managing my reading list, especially for currently on-going manga series.) But it still depends to a lot of elements; I mean would I like a poorly dragged down story just to say I love long series? Nope, chances are I might drop that series. And lemme say this I have tons of those kinds, and the frustration is carved to my otaku bones! But there are manga series that sustain my interest despite the length! Let me get down to the nit and gritty now!
First let’s cover some bases: manga series are most often than not is composed of story arcs with still one ultimate main plot. Story arcs are vital—it leads to better exposition! I wouldn’t argue the necessity of it! And plus most long series have wide variety of cast and this is also use to develop characters (among other important things). What I love about these arcs is how it connects to the grand scale of things! Then there arcs the feels like fillers—but let’s stay that aside for a moment because that’s also one long argument. Saving it for another day!) so for long series to a be a success it boils down to pacing, development, and consistency!
I think I cannot exempt one long manga series that didn’t suffer from the length. ワンピース (One Piece) used to be a favorite title! But now, I don’t know if I’m gonna get back to it or will it be like ナルト(Naruto) or ブリーチ (Bleach) that I’m waiting for the ending (not with bated breath obviously). People may argue with me (at least I knew some agree with me) that there’s dip with the quality—and with that my interest. At least Naruto before it ultimately ended I was curious enough to read 1-2 arcs prior the ending. Bleach, I just read the ending. And that was it for my Bleach reading experience because I knew; all fans of the series knew that Kubo had troubles! Apparent in his work I’m afraid! With One Piece which is now running for more than 2 decades??! That’s too freaking long!
Oh don’t me start with series like ハンター×ハンター (Hunter X Hunter)? I started following the series in 2002. I’m pretty sure some of you were babies or little kids at that time. Me? I was already freaking out with Hisoka. Now, 15 years later I still can’t see the freaking ending on the horizon (all thanks to Togashi persistent hiatuses)! I’m literally getting older here! I’m not sure if I’m up to the task but damn Togashi and his storytelling skills, I love to hate him, seriously!
For shoujo series, I really like series that are not too short but not too long, anything under 100 chapters but not less than 50 is I think an ample of time to develop all important aspects, particularly if the genre is romance-centric or slice of life. Admittedly I got tired with 君に届け (Kimi ni Todoke)—but still hasn’t totally lost interest since I check it every now & then.
But then there are series like スキップ・ビート! (Skip Beat!), which is in fact a shoujo series! Almost a decade following it and yet I still love it up to this day. Nakamura-sensei managed to hold my interest. Granted there few arcs that I didn’t really love (not hate the way with the shonen series) I still will follow it—gray hair, wrinkles, and all!
I think with manga series, it’s important that with your series to mature the way your readers mature in RL. I remember I read this apparent interview with フルーツバスケット (Fruits Basket) author, Natsuki Takaya-sensei, she said it’s imperative that your story mature the way your reader’s think. Some of her fans were teens when Fruits Basket started and by the time it ended some were already a full pledge adult *ahem* I think that’s nice way to think of readers, of us—if I may so myself.