I don't use nearly as much cash as I did in the past. I use my credit cards and pay them in full at the end of the month so I have no interest charges.
The main reason I use them is for rebates. I get 5% back on all gas and office supplies. I get 3% back on all groceries, restaurants, pharmacies, entertainment and fast food and I get 1% back on everything else.
This adds up quickly and the rebate checks are like Christmas presents.
I feel much safer using credit cards than debit cards because more safety features are built in. I also get free and extended warranties on items I purchase with them and lots of other goodies like rental car insurance, payments for lost luggage and many other free travel services.
In most personal transactions, cash is always best.