Charging current partly depends on the capacity of the battery. The manual for the Maha C9000 advises against charging below 0.3C or above 1.0C, where C is the capacity of the battery. Within that range lower is better for the battery but takes longer. Higher currents tend to over-heat the battery, which is less of a problem with good ventilation. Lower currents make it harder for a smart charger to detect when the battery is full.

AA Eneloops have a capacity of 2,000mAh, so the range is 600mA to 2,000mA. AAAs are around 750mAh so the range is 225mA to 750mA.

I would suggest using 0.5C, or half the capacity. That's 1,000mA for AA and 400mA for AAA. The C9000 defaults to 1,000mA.