There are several libraries that have been around JSP like JSTL, DisplayTag, etc. that you can use if you choose to go with JSP. With Freemarker, there are not as many of them.
JSP is tailor made for Web pages, FTL is a more generic templating language - it can be used to generate html, plain text, emails, etc.
To pick one, you must consider what kind of tools you have. All good Java IDEs have excellent JSP support. FTL support may/may not be as good.
