I prefer using cash, but I do use my debit card some too. I generally only keep about a hundred bucks on me, but I can put my hands on a couple grand or more in short order.
I have over three times my wife's annual salary stashed in case of a catastrophic event, and I'm working to save more. My Dad was diagnosed with cancer in May and died in September, and because of his financial planning, my Mom is doesn't have to worry about money. If something should happen to me, I don't want my wife worried about how she will make it financially.