Personally, I find the Sun chain of papers to be more supportive of the Conservatives. Yes, the National Post used to be THE Conservative periodical. However, I don't believe that is completely true anymore.
The Post was bought a few years ago from Conrad Black by the Aspers (bigtime Liberal party supporters). The changes in the beginning were subtle but it has been a steady decline since. Bye the way, this is why Steyn left - virtually coincided with the day the Aspers took over.