Hi,
I am not sure if the ranking actually matters in your case because first, University of Ottawa is among the top universities in Canada. So if you are going to stay in Canada, the Immigration office will consider you graduating from their top universities. Second, the main fact that you need to take into consideration is the country need for immigrants; Canada welcomes more immigrants than UK, therefore, you have more chances to stay in Canada after graduation. But it also depends on finding a suitable job right after.