When deciding between XML and JSON for data integration, both formats are prevalent, with XML being more human-readable and structured, while JSON is lightweight and closely aligned with JavaScript, making it popular for web applications. XML is derived from SGML and is used for structured data like database tables, often preferred for its strict schema and transformation capabilities through XSLT. JSON, designed for data exchange, is easier for developers due to its simplicity and compatibility with JavaScript, resulting in smaller message sizes. While XML is used in many contexts, JSON's leaner structure and ease of use in web environments give it an advantage in SaaS development. For existing APIs, data format conversions may be necessary, for which tools like Prismatic's embedded iPaaS can facilitate transitions between formats like XML and JSON.