Check the price and services differences between GS and Allstate Motor Club. Allstate is who GS currently contracts with for their ERS plan.
FMCA and Escapees both offer ERS plans from Saferide Motor Club, a 20+ year old ERS provider with pretty much the same features as GS/Allstate and Coach-Net. FMCA's plan is $69/year plus their $50/year ($60 first year) membership fee, and the Escapees' plan is $99/year plus a $40/year membership fee. For either organization, look at the total package of benefits beyond their ERS offerings when deciding which one is the best fit for you.