Social justice is a broad field. If you're looking to work on the micro/local level (community legal clinic, working as duty counsel, real estate, counsel at other community-minded organization), experience trumps school. Broader social justice organizations like Amnesty International, or boutique SJ firms are competitive AF. Experience is still huge though some of the "more competitive" schools seem to be represented more.
I used to work in a social justice position in SW Ontario. There were plenty of Windsor grads out there. The hiring organization doesn't care whether you went to a school that places half the class into big law because that's not relevant.
Queens international reach might be better than Windsor though they're both behind U of T, McGill and, to an extent, Osgoode.
Both are good schools. Going to Windsor over Queens is not some kiss of death or career suicide. Go where you will be able to succeed to the best of your abilities. Consider how easy it is to see family and friends, travel costs and where you can envision living for 3 years.