So I got interested in this topic and did a little research onto the three planes they are now looking at. Cheapest overall by a pretty fair margin Is the Gripen (40-60m U.S). Followed by the Dassault Rafale depending on variant Canada wants (82.3-124m U.S) Eurofighter well, 90m pounds to 143m pounds doesn't seem very good at all.
As mentioned before Gripen has the STOL capability. Gripen is a much smaller plane than the other two which means it carries a much smaller payload.
After reading more than five or six comparisons between the Rafale and the Eurofighter, it seems pretty consensus that Rafale is essentially the same plane with a very small advantage in thrust, maneuvering, range and payload. So by deduction one would choose the Rafale over the more expensive Eurofighter. I also believe I read that the Dassault radar system is slightly better as well. But the eurofighters overall computer system is better by a fair margin. including better measures to be "almost" stealth. Eurofighter is also built by four of Europe's leading aerospace companies versus the Rafale which is built by..well.. the French. If I were to go on looks alone I wouldn't buy either of these two or the Gripen for that matter as I am not a huge fan of delta wing aircraft.
Now, that being said. The Gripen although short range can be bought at pretty much 2 for 1 comparatively and the technology is much cheaper to upgrade through Saab as it comes along. So just in sheer numbers alone we could cover our airspace just as well. Maintenance costs are also severely lower than the rest as well. Also read that Gripens aviaonics at this point in time are actually better than the other two jets. Payload is half that of the Rafale but again you can buy two Gripens for the price of one Rafale and almost four to the cost of one Eurofighter.
I guess this post is rather meaningless without me plagarizing all the info I just absorbed. But I look at it like this. There is always comfort in larger numbers. Id rather have a small army up in the sky versus one or two really really fancy planes that we cannot replace if one gets shot down. I really do think the Gripen has excellent bang for its buck.
Edit: Been reading some more and seems like Dassault is having a sale on Rafales, I read as low as 45m but that could be barebones and not updated software. Gripen also uses the same engine as the Hornet. that makes more sense to buy the Gripen then.
http://www.youtube.com/watch?v=Cy6DJSVolv0
Here is a video I watched last night on the three.