Should I use cookies or local storage for cart tracking?

As a Shopify store owner running multiple product lines in fashion and accessories, I've been wrestling with the most reliable way to track customer cart interactions. My current setup involves standard Shopify tracking, but I'm noticing inconsistencies, especially with mobile users who might switch between devices or accidentally close browsers. I need a tracking method that's robust, respects user privacy, and provides seamless cart recovery. My development team keeps debating cookies versus local storage, and frankly, I'm more concerned about the bottom line: will this impact conversion rates? I've seen abandoned carts spike during holiday seasons, and every lost sale feels like money walking out the door. My primary concerns are data persistence, cross-device reliability, and ensuring we're not accidentally exposing sensitive customer information. Some of my team argues local storage is more modern, while others swear by traditional cookies. I need a definitive answer that balances technical performance with user experience and doesn't require me to become a JavaScript expert overnight.