All good recommendations here. The way that I "choose" a battery for a mod is by math.
Steam engine's "Ohm's Law" tab is great for that. Keep in mind that in a regulated mod, the resistance of the atomizer is irrelevant, the circuitry is going to pull the required current out of the battery to "make" the desired power.
For example, let's say that you want to send 50 watts to your atomizer, and the low voltage cutoff for your mod is 3.1 volts.
Power = Voltage X Current. You know the power and the voltage, and solving for current gives you 16.1 amps. I'd be happy with a good 20 amp battery in this case.
And to add another battery to the mix, AW has a relatively new 18650, 3000 mAh and a CDR (Continuous Discharge Rate) of 20 amps. That's really pretty good, considering the capacity of the cell, and they're also rated for >500 cycles, and that's darn excellent!