Richard, I'll give you my opinion but many I know will disagree. That is the nature of forums such as these.
As you know, FMCA doesn't administer their ERS themselves but rather contracts their "Roadside Rescue" service out to an outfit called SafeRide. SafeRide has a relatively good reputation. I believe that the Escapees also use SafeRide for their ERS. This is similar to Good Sam where they contract their ERS also ...I believe (and somebody can correct me if I'm wrong) that Good Sam uses Allstate and the Allstate ERS call centers.
For us (and we are now retired from RVing), we couldn't take the continued escalating prices for Coach-Net that we used for quite a few years. And once Coach-net raised their prices and packages to levels that I just couldn't justify, we went with SafeRide for our last few years. We never used the service so I can't comment on that but the price was right.
My theory (and this is where many will not agree with me) ERS is like any other "insurance" service. I usually go with high deductibles with our insurance policies and insure for the catastrophic events. I'll also self-insure for mechanical breakdowns so never buy extended warranties or service contracts.
Therefore, because we've hardly used ERS through the years, I'd rather go with the least expensive. But again, that's just me. There are plenty of people here that will argue with my logic and prove me wrong with their own experiences.
I read in one thread here on ERS (and as you know, there are dozens and dozens of threads here and on other RV forums about ERS) that one guy pays for Coach-Net, Good Sam, FMCA/SafeRide, and AAA ERS policies as he claims he wants to be covered no matter where he is or what the problem he may be having and have plenty of back-up should one not respond fast enough or in the manner he expects. To me, that's just overkill and a waste of money to be paying for four ERS policies but I'm sure many don't agree with how I feel.
So my opinion is to go with FMCA's SafeRide. Most of the ERS call centers basically will use the same providers anyway in any given area under the same circumstance.
And I read on one forum --and I have no idea if this is true or not-- that SafeRide has the reputation of paying their service providers quickly so in turn, providers are quick to respond to calls from their call center and that could be a benefit of having FMCA over GoodSam/Allstate. Again, who knows.
FMCA Roadside Rescue comparison chart
SafeRide Motor Club general website