Which is better or more convenient to use:
or
Both will work but xhtml standard requires you to specify the type too:
type = content-type [CI] This attribute specifies the scripting language of the element's contents and overrides the default scripting language. The scripting language is specified as a content type (e.g., "text/javascript"). Authors must supply a value for this attribute. There is no default value for this attribute.
Notices the emphasis above.
http://www.w3.org/TR/html4/interact/scripts.html
Note: As of HTML5 (far away), the type attribute is not required and is default.