Twin engine, superior range, speed, and endurance over either the F-35 or the F/A-18E/F, larger payload, and affordable.
Second choice should be F/A-18E/F, although commonality with the CF-18 is mostly cosmetic.
F-35As made sense when the decision was first made almost a decade ago, because of the tremendous capabilities for the money. But with the price creep and delayed service entry date of the F-35, the CF-18s may not last long enough.
And if anybody thinks Canada no longer needs an Air Force, remember who patrolled our skys when our entire fleets of F-15Cs were grounded due to structural issues a few years ago.
They committed to the deal and they should stick with it.