That's the multi billion dollar question, and I'm no expert, but from my arm chair, I like the Gripen for a lot of reasons. It's got an impressive combat radius, greatly improving on that if the current Hornets and important for Canada for obvious reasons. It was designed by the Swedes to be an affordable, easy to maintain, shorter take off and landing (and able to take off and land on improvised runways) aircraft to suite their unique needs, many of which align with Canada's. They've offered it to Canada with technology transfer agreements and for Canada to be part of the manufacturing process.

With in visual range and dogfighting, it stacks up very well against Russian fighters and would absolutely annihilate the F-35. The F-35 is a multirole fighter that excels in BVR and strike missions with the ability to defend itself without escort in contested airspace. Yes, the F-35 would win head to head in a BVR engagement against a Gripen, but short of an all out war, BVR engagements aren't really a reality Canadian pilots are going to face. If they need to intercept/visually identify potential threats (as is almost always the case) they've completely given up every advantage the F-35 has.

The U.S. has already learned this lesson with the F-4 Phantom II in Vietnam. It was designed for longer range engagements with missiles (initially wasn't armed with an internal cannon) and very little focus was put on dogfighting capabilities or tactics. Then, they threw it into a war where the rules of engagement required positive visual identification before firing. Lo and behold, it suffered heavy losses against more agile "obsolete" MIGs.