I am currently pursuing my PhD in computer science at a mid-rank US institution (ranked 50 in US-news graduate computer science ranking). Assuming I have a decent publication record and good references. Would I have better chances of securing a postdoc position if I applied to openings in the US or would I have better chances if I applied to openings in other countries such as Canada, UK, Australia?
I agree with Alexey B. regarding higher chances of being accepted in institution which have one or more research groups in your area despite the country. Also, i would like to add that here in Europe it is highly suggested to spend your postdoc period in another country. This will show that you are truly independent when it comes of research. Although i am not sure whether this apply also in USA or in other countries you might want to consider this aspect too.