There are some lovely educational opportunities in the maritimes.
McLeans magazine has the Canadian university rankings and information each year that many students find helpful. University websites, taking a tour, asking other students about their experiences will point you in the right direction. The quality of the food, and whether or not they schedule final exams for Saturday nights at 7 pm are important.
The best university for you (thinking cost wise, your interests, whichever career(s) you may want to consider after getting a degree) may not be in the city with the best job market. If you're thinking of working and getting a degree at the same time, remember there are plenty of other students trying to do the same thing. Search for a summer job January/February/March, and you're fine, usually.
That being said...you need to do a fair bit of research to chose a university.
You must check very carefully as to whether your classes from your associates degree may be applied to a Bachelors degree. How many of them, which of them, if any, count as credits will depend on the university. They may need to see a course syllabus.
Look at the 3rd and 4th year classes offered at different universities (presumably in math, or other departments). What prerequisites do you need, and what looks interesting. Your major won't determine what you do with the rest of your life, but you don't want to be bored for the two years of your degree where you do a lot of learning.
What size city do you want to live in?
How good is the university library? (Do they have subscriptions to the important research journals in your field, friendly reference staff, nice computer labs? How late are they open?).
Tuition does vary between institutions, as does the cost of student housing. Do your student fees cover public transit during the school year? Living further away from campus is usually cheap(er), as is living with roomates. The search for an apartment isn't often easy. Some people reserve a place in June, others show up a month early to look, in my neck of the woods. Finding someone who needs a roomate may be an option.
Are differential fees going to apply? If you aren't a citizen or permanent resident of Canada/ or are not a resident of the province, you may have to pay extra. This may have a big impact on your budget.
I like the winters here. Aside from people not clearing their sidewalks, its good. Fairly mild.