I've had Embrace Pet Insurance for my dog Baxter since we got him a year and half ago. They have always been prompt and accurate in dealing with the claims I've sent it. And when a refund is due, they have it deposited into your bank account quickly.
I chose Embrace because they are one of the few pet insurance companies that will cover genetic / hereditary problems with dogs. I have two pure bred French Bulldogs - which are very prone to health issues. So its nice to have the piece of mind that if they do have issues with breathing, hips, spines, eyes, skin, etc ... that i should be covered.