Cost per hour in the air is the key. A Porsche is expensive...but operational costs are much lower 
than a Range Rover. Over the lifetime of a plane, the key is cost per hour.

The f 35 can survive the first day of war in a peer environment. The Super 18 cannot. the Super 18  can be used as a flying  arsenal by F 22s and F 35s until the enemies' defences are eroded.  So the choice defines the RCAF role. 

I think we should avoid the first day, buy the Super 18 and have a solid 2 engined aircraft for arctic sovereignty and ground support.