Firstly, congratulations on 3 accepts!
I'd pick Kellogg, unless the full-ride from Tuck or Yale is extremely important to you. But I believe the brand, network and resources of Kellogg will make the cost of Kellogg worth it.
Kellogg is consistently ranked higher than the other two, and while I try not to look at rankings, Kellogg is also in the M7 - group of elite business schools. I also think the course work and offerings of Kellogg are unmatched; there appears to be a good mix between case method, experiential learning and group work. It's established and big enough that there are opportunities to go into any field -- and over the last decade, it's increasingly entrepreneurial.
For your career goals, Kellogg is great for consulting recruiting (particularly for MBB) and has a really strong social impact / innovation focus. I'd argue that only stanford rivals Kellogg's focus on social innovation. Check out their KIEI (their innovation and entrepreneurship initiative) and the many social impact courses). Also, I believe Kellogg's Net Impact chapter won best chapter last year -- their strong net impact chapter is a good sign that'd you'd have like-minded peers interested in social impact.
All this said, I do think Yale has a very strong reputation for Non-profit management. So if social impact for you means working at an NGO, I would pick Yale over tuck.
hope this helps a bit!