What role does the jet have to fulfill? Fight off enemy planes in an invasion? If it's the US that invades you wouldn't want US tech, but it doesn't really matter, the US would win. Russia invading? At this point they're down to kites and helium balloons, right?

If it's to fulfill a role within NATO, a Gripen is probably just as good as an F-35, because any enemy of NATO's will almost certainly be many generations behind. China wouldn't be, but neither Canada directly nor NATO is likely to get into a direct fighting war with China. Only maybe if Canada wanted to help defend Taiwan against Chinese aggression could that possibly happen. But, because Taiwan's a small island, Canada's Navy would probably be the main force involved.

In a few decades, things might already have changed. Missiles and drones might have made fighter jets essentially obsolete. So, it doesn't make too much sense to buy something that's massively expensive just because it's the most up-to-date thing right now.