While Culvers is way near the top (I mean Cheese curds, am I right?) I have to admit my fast food drug of choice is still Burger King: Their fries are crispy and they have the best processed chicken chunks out there!
Don't know really, but there are no White Castles in Canada so I have no idea what they're like aside from that movie Harold and Kumar Go To White Castle. That's about all I know of it. As for fast food places, I rarely go to them, sometimes it just makes me gag so Subway is usually where I would go first.