Subway is probably my favorite fast food chain overall, as there is a metric ton of variety compared to most other fast food places, and the ingredients that go onto the subs actually resemble "real" food, so I don't feel like I'm getting ripped off buying some overly-processed junk.
As strange as this may sound, I'm also a fan of McDonalds. Their fries are amazing, their burgers are like meaty, greasy delicious gut-bombs, and best of all, they're cheap! Of course, I probably wouldn't be as much of a fan if I actually lived in a community that had one, and since I've pretty much lived in various small towns all my life, McDonalds has always been a once-in-a-while thing for when I go to a major center.
I used to be a Taco Bell fan, but then one day I discovered that the two things I usually got there (a crunchwrap supreme with fries supreme) were the only decent items on the menu. I still enjoy getting them once in a while, but usually I prefer just to make my own tex-mex stuff at home. It's cheaper, higher quality, and probably healthier as well.
A&W is another solid chain, and you can find a location for them in practically every small town in Canada. They've got good burgers, good chicken, and they have poutine made with actual cheese curds!
They don't seem as special to me as the other chains though, since their fare is more "pedestrian" than Subway, and I've eaten there 100x as many times as I've eaten at McDonalds.
Wendy's and DQ are awesome once in a while too, though I still prefer Subway and A&W for the most part.
Dang, now I want a burger. XD