Coopers are good from what I hear. I'm a Goodyear guy, never had a problem with them got 60,000 on my first set of MTR (originals) and now I'm with the duratracs, absolutely love them and if you live where you get snow or wet roads, you can't. Beat the performance. Tires are like everything else, so times a few bad ones sneak out. When your dealing with 100,000 + in production you just can't inspect them all, so you batch test! this doesn't mean some bad ones get to the consumer. Also you get what you pay for, GY, has tires for the economy minded individual and quite simply you won't be happy.
Look at the weather and road conditions around your area, and buy accordingly, prices have increased over the years so expect to pay 600-1200 for a set of average 4runner tires.