I can give my perspective from Trent.
LGBT rights are advocated for highly here, and everyone is very inclusive of people of all sexual backgrounds. I know several people who are a part of the community, and the discrimination they face at Trent is minimal (relative to other places that I'm used to). Trent is kind of famous for this point.
In terms of least snobby, Trent seems to have the most down-to-earth people I know. Being pretentious is frowned upon by most I'd think. Many people come from small towns here and bring that small town friendliness with them. Getting into conversations with random people on Peterborough buses is quite common too, which is nice as it makes you feel a part of a true community.
In terms of cultural diversity, Trent tries hard to promote it. TISA (Trent International Students Association) is one of the biggest and most powerful student organizations on campus. They run several of the most anticipated and well-attended events on campus. The aforementioned small town people are sometimes ignorant of certain cultural concerns, but they truly do mean well almost all the time. They just never really had the chance to interact with diverse populations in high school.
Also, despite having a predominantly white campus (I think it's somewhere around 75% if I had to guess?), most of the elected people who get elected to our central student government are members of minority groups (in some way, not always culturally but often so).
If you're worried about fitting in, Trent is definitely your place as it has the most welcoming community I know of. This is the reason I dread coming back to all the problems in Mississauga so much when schools out of session.
Queen's-Trent Concurrent Education, '14 (Trent B.Sc) and '15 (Queen's B.Ed)