When choosing the best payment gateway for your e-commerce business, you should compare more than just costs. Reputation and reliability are key factors to consider, so you should research the payment gateway's track record of performance, security, and customer service. Additionally, verify its certifications, accreditations, and compliance with industry standards and regulations. Compatibility and flexibility are also important; make sure the payment gateway is compatible with your website or app platform, payment processor, and other business tools and systems. Check its documentation, API, and SDK to see how easy it is to integrate and customize. Additionally, evaluate the payment gateway's scalability, availability, and support to handle current and future needs. Finally, consider features and functionality such as payment methods, currencies, regions, languages, checkout options, reporting, analytics, fraud prevention, and customer support.