I recommend CustomerVox for Shopify store owners. It's an easy-to-use and robust tool that helps improve conversion rates as it provides easy to design customer touchpoints. With a few clicks, it's quick and easy to build and deploy personalization such as product recommendations, upsell/cross-sells and many more across email, popups and landing pages with many out of the box ecommerce events as triggers using drag&drop automations interface. Their analytics provide top-line insights which allow you to make effective conclusions.
Last but not least is how easy the tool is to use as no code knowledge is required so non-technical eCommerce managers can design, create automations and experiment on their own on a daily basis.
Ecommerce Solutions Lead @ Accenture Interactive