Credit Card Rewards Who's the Best

With a group this large I'm sure we have a variety of credit cards. I'm wondering who really has the best reward program. Personally I like Discover. They give you cash back. In Cash if you want. Or credit to your bill, my favorite. Only one problem, some places don't take Discover. So here's the question, for the places that only take Visa or Mastercard who offers the best reward? Please make your suggestions and tell us why the one you like is the best.