I haven't had much luck with Champion plugs. As previously stated, misfire codes and poor spark seem to be a problem. I think Champion products went the way of Fram, i.e. they used to make great products but now are just cheap low end products with a big name label.
It all really depends on the engine and what it likes. I know for a fact that Honda engines don't like Bosch or Champion plugs. They start to run poorly and eventually misfire. When a car comes in our shop with misfire codes the first thing I check is the plugs. "Let's see here. Bosch Platinum? Yep, here's your problem."
Seems that a lot of the bargain auto parts stores push Bosch Platinums for everything. Which is great if you have a German car, but not so great for others.
As for Champion, I'd use em in a lawnmower. But not my car.