I think JSPX files are JSP in XML syntax and JSP files are the regular JSP files.
You can use either regular JSP syntax or JSP in XML syntax to achieve the same results, but I was reading in JSP 2.1 specificiation that the development of XML syntax was limited.
So I would recommend JSP syntax.
But if you want to generate XML like JSP pages for whatever reason then use JSP in XML syntax.
Other best practice solutions are to use JSTL instead of scriptlets, as it leads to cleaner and easier code. JSTL is easy to learn.