What is a good middle ground college?

Higher than Boston College but lower than Harvard

For, say, nursing, as well as with respect to perhaps other fields or personal preferences, BC may be “higher” than Harvard.

However, to address what I believe you meant by your question, there might be about 39 colleges that would fall into the relatively narrow selectivity gap between BC and Harvard:

http://www.businessinsider.com/the-50-smartest-colleges-in-america-2016-10/#4-harvey-mudd-college-average-sat-score-1500-48

All great schools and all highly selective so not certain that “middle ground” is the right way to look at those goal posts!

This isn’t really enough information. Are you interested in public or private? Large or small? What area(s) of study are you contemplating? Is geographic location important to you? Cost?

Aren’t you in 8th grade? I think you should spend more time focusing on the geometry class you’re struggling with and less time worrying about college rankings.