<p>If the Dartmouth internship is a done deal, I would go with that. However, either would be fantastic. Which internship you take is not going to make or break your college admissions chances at any school.</p>
<p>Both opportunities are research internships, and I do not think colleges will look at them too differently. Perhaps you should look into where each one could lead. What really matters is what you make of an internship, not how smart your PI happens to be.</p>
<p>To be honest with you, those are two fine choices. Just pick whichever one you get first, and do not look back.</p>