I'm someone who likes it in the middle. I've seen plenty of comics/mangas that just dragged on and sorta ended abruptly (granted, a lot of them had interference from outside sources, and as a reader and creator, I take a lot of that into account). Some even have filler, which can confuse the reader with where the storyline is going.
Then there are those that are too short, and I'm left with a lot of questions that most likely should've been answered in the story (again, outside sources can play a part in that, especially if a creator is rushed).
I think, in the end, as long as I know what the story is and I see the characters grow over time, I'm all for it -- whether it's long or short.
I know I have a few stories that are both. One story I have (Tainted Tears, Tainted Perspective) is like 10 chapters or so long. But another one I have (DOLLS) has over 260 chapters in the making. I guess it all depends on how much you needed to develop the story ad its characters 