Consumer Reports just did an article on car batteries, but their tests don't reflect the demand that ELB members might need because of emergency lights and two-way radios.
As discussed in this thread, a lot of factors need to be considered in choosing a vehicle battery.
The configuration (side or top terminal), make of vehicle, and climate zone (North or South) figured in the results. Duralast batteries from Auto Zone were ranked lower than in the previous studies, but you could buy two of them for what an Optima Red Top cost. Die Hard top terminal batteries seemed to perform well in Fords, but other brand batteries proved better in Chrysler, GM SUV and sedans, Toyota and other Japanese vehicles.
And, . . . If an emergency vehicle is not equipped with an upgraded capacity alternator, many quality batteries may fail prematurely because of the amp load and current drain.