Space issues - manga in the library

I was really excited to recently be able to buy some new additions to the library's manga collection. To date, most of our manga has been collected from donations, and as such there are very few complete series. However, space is extremely limited in my teen section, and as such I can't actually put all the new manga I've aquired on the shelf! (I've got a temporary fix by placing the new stuff in a different location by the entrance)

So now I'm left wondering, when space is such an issue, yet graphic novels and manga are so desired, what is the better option, to have complete series, but less overall titles, or have bits and pieces from different series but have a larger selection? I feel like right now I'm in a weird middle ground, with chunks of manga here and there, and then like almost 50 volumes of Bleach!