Canada’s main priority is defending our land. Every fighter we’ve purchased since the 50’s has had that in mind, we need to be able to fly to the arctic to protect our sovereignty, and protect our country from threats. In terms of sovereignty, our biggest aggressor is Russia, who does have a superior air force. They’re known to poke into our airspace from time to time to remind us of their presence.
In terms of protecting the arctic, twin-engine planes are the best as they provide the extra-security and safety; so the F-35 is a no-no in that regard. No one wants their only engine to die out over cold arctic ice and water. Hence, why the Canadian designed Avro Arrow (designed for our usage) had 2 engines, we also had the 2 engine Voodoo for a while, and eventually we procured CF-18s. A single engine fighter simply doesn’t fit our criteria.
Flying across the country is an important component for our military. Not just to maintain arctic sovereignty, but to protect the nuclear power plants we have as well. I’ve read somewhere in the past that theres a few CF-18s stationed in Trenton to protect the Pickering Nuclear Power Plant. Our (previous) governments have always favoured twin-engined jets as they’re more reliable for this purpose.
And to tap into your ISIL point, we should never underestimate our enemies. Conflicts change all the time. We could be fighting ISIL now, and a country with a decent airforce later. We should always prepare for the future. And taking into account the aircraft we’re considering buying (F-35) can’t even shoot down a fighter jet designed in the 1970s shows that we’re taking a step backwards, not forwards.