I personally love Nana. But I would keep the villagers you find the most "interesting", and have the closest relationship with (if that makes any sense).
For example, I have three normals: Lily, Nana and Savannah. I love them all, but if I were forced to let one go, I'd let Lily go because I find her dialogue the least interesting out of the three of them. I find she repeats herself a lot, and says the same generic phrases quite a bit, whereas Savannah says different things all the time.
That was kind of ramble-y, but hopefully it helps a bit. xD
that totally makes sense! i think about the same thing.
