As a soon to be university graduate who researched universities in 4 continents, all i can say is that rankings do matter but not to the extent some ppl make it out to be.
For e.g., if 2 universities r ranked 6th and 8th in Macleans, there is virtually no difference in them. On the other hand, there is a difference between 3rd and 15th.
Rankings matter only because some employers may look at the quality of ur university when u r applying for ur first job. But the importance of rankings is less than that of how capable as a student u r or ur communication skills.
Simply put, if 2 graduates from the u of toronto and memorial univ of newfoundland have similar communication skills and grades, the U of T guy will normally be preferred.
Once u get job experience ur univ status takes minimal importance.
when u apply for a job 15 years from now no one is going to dig up rankings and find out ur university's position.
btw what subject r u studying? i can advise u further if i know the degree area.