Hi! I also applied to NIU, and I am kinda confused about what to think.
My parents both went their for undergrad and my Grandpa was a professor there (a million years ago), so I have a personal and emotional connection to that school. I am from Illinois, and in my opinion NIU is not up to the same caliber as most of the schools I am applying to, so I never expected to find a research there who I would really want to work with. However, the PI I am working with now recommended the POI I applied to work with and has said that they are an excellent researcher. My PI absolutely would not say that if it was not true.
I don't know if this will help you decide at all but I hope it helps some. Feel free to private message me if you want more information: POI, my PI, etc.