You get the coverage you want by specifying it, e.g. the liability limits, collision & comprehensive, deductible amounts, personal property coverage amounts, etc. If you don't do your homework and just ask for "RV insurance", you get whatever default package that agent likes. It may well be designed to maximize his commission rather than suit your needs. Rarely would you have to change companies to get different coverages or amounts. If you don't understand the difference between liability and collision or what the associated terms mean, you afe probably doomed to be disappointed if you ever file a claim. For example, replacement value vs market value is a crucial difference in collision coverage. Replacement value provides more financial protection, but it also costs quite a bit more. Buying extra insurance coverage is a financial risk decision.
I haven't found much difference in customer service among the major carriers and all have been OK in my dealings. I suppose it depends on what service you want, e.g. upfront assist from the sales agent or back-end service for a claim. Those are handled by different people, so a friendly sales agency doesn't guarantee equally friendly claims help.
A few of the considerations are: Fulltimers generally need more insurance and higher dollar amounts because they don't have home owner or rental insurance as a back-up and all their possessions are in the RV. But if you do have home owner insurance on a dwelling somewhere, you probably do NOT need the so-called "campground liability" or a lot of personal property coverage, cause the homeowners does that for you. If you have a loan on the RV, you probably want to make sure the collision and Comp coverage will at least cover the loan balance.