How long will the F-35's stealth technology remain effective? I don't think Canada needs the F-35 - looking at the country, a tough twin-engined fighter with a long range would prove far more effective. Something like the Super Hornet, Rafale or Eurofighter. The French are more than satisfied with the Rafale and aren't rushing into developing stealth aircraft.
And look at Russia and how effective its MIG-31s and SU-27s are proving at patrolling the massive expanses of airspace there. The F-35 is too expensive and is not an aircraft that suits Canada's needs. The added safety of two engines, more fuel and weapons would be far more effective in my opinion.