Keep in mind that if you rely on your own car insurance, it will have a deductible. Many credit cards offer coverage, however a lot of them are secondary which will require you to file a claim through your own insurance first and then the credit card CDW will kick in and cover the deductible that you had to pay.
If you have different cards, check out the CDW coverage that they offer. Some have primary CDW. We use the Chase United Explorer card for all car rentals since it offers primary CDW coverage.