Make sure the battery has at least 8 bars left. There's two gauges on the dash: current charge and battery capacity. Capacity is the skinnier one on the right [0]. If you find one still within the warranty window below 8 bars, Nissan will even replace the battery free [1]. Also make sure you get one with a quick charge port, it's worth every penny. Other than that you really can't go wrong.
Not an owner, but I think those two points work against each other a bit. How much, I'm not sure, but slower charging does preserve capacity. If you have no plans for long trips where you need to charge during a meal, and will always be charging overnight or while at work, batteries that haven't had to deal with faster charging could be better.
You're not wrong however all of the studies and research out there shows the degradation is hundreds or tenths of a percentage point. In other words it's insignificant.
