I went with this one: New Battery FX30 for Motorola Moto X Pure Edition XT1575 Style SNN5964A XT1572 https://www.amazon.com/dp/B076QK3YK7/

It was less than $20. Looks like the OEM battery.

EDIT: Please see my post further down the chain for more info -- this battery stopped holding a charge after 2 months.