If you’re worried about going to a place where marijuana has been legalized, you can pretty much forget U of Toronto and U of British Columbia, since both recreational and medical marijuana are legal in Canada. Medical marijuana is legal in both Illinois and California, but not recreational marijuana, which covers both UCSD and UIUC. Laws regarding marijuana in Urbana and Champaign are the same as in the rest of Illinois.
So, I would recommend that you stop worrying about whether marijuana is legal.
Tuition (CS) + fees + book/supplies/other + room and board:
UIUC (International) = $56,807
UCSD (non CA resident) = $60,027
U Toronto (international): about $45,000-$50,000 (American Dollars)
UBC (International): about $44,000-$47,000 (American Dollars)
I’m not entirely sure about things like medical insurance in Canada, so it may be $1,000 or so more a year.
Every one of those universities has a world class Liberal Arts education.
UIUC is probably the safest of them all. Among the three urban campuses, the city of Toronto has the highest rate of violent crime, followed by Vancouver, followed by San Diego. I cannot find data on crime rates on the campuses themselves, though.