We shopped around for insurance and you pretty much got what you paid for.
However, if the trailer was totaled in an accident, only one of the companies would pay the purchase price rather than the current market value. That was Progressive.
Since we were new to RV towing, we figured purchase value insurance was a good idea for the first year or so. :W
In our case adding it to our home/car insurance was by far the cheapest option, but not surprisingly, it also provided the least coverage and higher deductible. In a few years we will probably switch to the cheaper insurance but now we are still in the learning stage.