I’m not going to make a recommendation per se to exceed specified performance limits, but based on the following, I think the best of the current 3500mAh cells such as the NCR18650GA are reasonable choices for this light for people with a good understanding of their battery’s limits. If in doubt, of course, there are good higher current cells like the 30Q easily available.
I only found one copy of an alleged NCR18650GA datasheet, from Orbtronics, who sell this cell and protected batteries based on it:
It did not have an explicit maximum current spec, but they show continuous discharge data to 10A. At this rate, in 22 Celsius ambient, it reaches the maximum rated temperature of 60 Celsius right at the very end of the discharge.
HKJ and Mooch both provided favorable assessments at 10A continuous. Both tested it to 15A with no observed issues aside from exceeding the specified (conservative?) maximum temperature during sustained use. Mooch even did a continuous test at 20A and a pulse test (5s on, 30s off, repeatedly) up to 40A! Those are clearly excessive conditions, but the cell held up. The Samsung 35E and LG MJ1, had nearly as good of performance.
I know all of these cells have been tested in the Emisar D4, which is a higher power light than the FW3A.
Neither of these lights are capable of continuous 10+ Amps without taking deliberate measures like water or ice cooling. In normal conditions, the sustained performance due to thermal control would be something like 2-3A.