Canada

With the shit that Russia is pulling now, we're going to be very glad we have these.

Stealth isn't just a "first strike capability", it's the cornerstone of all modern combat. The way you win any fight, on the ground, at sea, or in the air, is by being able to engage the enemy before they can engage you.

Right now Russia does not have a true stealth capable fifth gen fighter. The SU-57 is, even according to Russia's numbers, "low visibility" at best. And Russia has maybe six of those. With the F-35 Canada outmatches every single plane Russia is capable of putting in the sky, to an absolutely ridiculous degree.

I don't like the fact that we have to think about questions like "What if Putin goes so far into crazy town that he actually launches an invasion of Canada through the Arctic", but recent events have demonatrated that that possibility really does exist, and we need to plan for it. Or, at least, we need to make the prospect so unpalatable that he wouldn't consider it.

And to head off a couple of obvious questions:

"But the Philippines just defeated a stealth plane using a regular jet."

It was carrying drop tanks. Under no real peer-to-peer combat scenario would that plane ever be carrying drop tanks. They completely ruin the stealth capabilities of the craft. Where Russia historically inflates the capabilities of their equipment, America does the opposite, always making their top tier stuff seem worse than it is so that no one can plan to beat it.

"But I've heard that the F-35 was an expensive disaster that can't do anything well."

The man you heard this from, once you trace the claim back to its source, will inevitably turn out to have been Pierre Sprey. Sprey got a lot of time on CNN and other news shows (including, frequently, Russia Today) as an "expert". He is not. He claimed to have designed the F-15, the F-16, and the A-10. In reality he sat in on one meeting about the F-15, and had basically nothing to do with the other projects.

Sprey was (he died a couple of years ago) a lunatic who believes that modern technology is too complicated and holds back the capabilities of well trained soldiers. You know, modern technology like radar and missiles. Sprey genuinely advocated for all aircraft to be replaced with single seat fighters armed with a cannon and nothing else (look up the "Blitz fighter"). He was an idiot who somehow lied his way into a career as an expert on TV despite having no actual expertise. The world is better for his passing.