58678d68_chmarking_AJAX___JSON_vs_XML____JSON
[Characteristic] Formatting decisions [XML] Complex. Requires a greater effort to decide how to map application types to XML elements and attributes. Can create heated debates whether an element-centric or attribute-centric approach is better. [JSON] 
Simple. Provides a much more direct mapping for application data. The only exception may be the absence of date/time literal.
Benchmarking AJAX ( JSON vs XML )
JSON