Co-op. I think it stems from my time in the military. There has always been something satisfying to me about working with others utilizing each of our own specific strengths, coming up with a plan, executing it and if it fails working together to improve our chances of success. That's way more satisfying than k/dr. Don't get me wrong as it is possible to have a similar experience while competing against an opposing team but a lot of times that ends up being more about individual skill and those who can take up more of the slack in most competitive game types. That being said I don't get as much satisfaction from the latter.