TRUST this opinion based on personal experience. Get the best coverage you possibly can but be aware of insurance fraud where they take the insurance money you paid them and just pocket it. They count on the odds that you will not get in an accident. Worse yet, if you do have an accident, you will pay the high deductible and they will pocket that too and then tell you to go to hell when it's time to make a claim or someone gets injured.
I was involved in a Jeep accident in Cozumel 12 days ago. I was sitting in the back of a rental Jeep (behind the driver) when we were broadsided. I took most of the hit and split my head open and was in the hospital for 3 days.
I will be posting about this in the next day or two but I have been royally screwed by this car rental company... and this is a company I have used many times in the past and to whom I refer business to.
For now, all I can say is: "Trust me, it is not worth it just to save a few dollars!"