I'm with AllState also for everything: Home, autos, life, RV, and even a couple investments. I don't think you can do any better than AllState. We've had to put a few claims in over our life-time, and AllState has always done us very good. They replaced ALL the siding on our PUP, then turned right around a few months later and paid for a hole in the roof on the PUP. Out of pocket was minimal compared to the total cost for both of these claims.
One thing to consider, if your happy with AllState for everything else your insured for,then you'll be happy having your camper covered too with them. If your not happy, then maybe it's time to switch. One thing is for sure, you get better discounts when one company has multiple policies with you.
I'm fairly loyal to AllState. Not because their prices are the dirt cheapest. Oh, you can find cheaper insurance, but you'll end up paying at the end with time, effort, and loss of use of your property (time and usage) if you ever do need to put in a claim.
Consider the total package, not just the premium price, but how good are they at dealing with claims ... and multiple claims in short succession.
Additional Edit:
You really need to consider all the factors when getting RV insurance, especially with a detachable trailer. You really need to be covered when your camper is:
1. attached to the tow vehicle (the tow vehicle policy covers in the event of a mishap.
2. detached from the truck when parked, either in storage or in use. The RV policy will cover this. Example: if your at a camp ground a tree falls on your roof, or a tornado blows it away, fire and theft. RV insurance covers this.
3. personal belongings or personal affects. Your RV insurance may cover this or your home-owners may cover this. Our home owners policy covers 100% of the contents inside the camper that's not screwed to the floor or wall. That includes laptop computers to ink pens.
4. bodily injury. Oh yes ... very important you have this coverage somewhere. If you have a garden hose across your campsite, and a kid trips over it and breaks his leg, YOU can be held liable for negligence and get sued and loose. If someone falls inside your camper, YOU are responsible. This is covered under our home owners.
However, if there's a hole in the ground on your campsite and a kid falls in it and breaks a leg, the campground is responsible.... see the difference?
A combination of these 4 insurance areas is why it's good to keep everything with one insurance company, they work together to protect you the most.