I faced the same dilemma about a month ago. I have been a seasoned developer using apache tiles, and I wanted to try something different.
I did some research and found that Spring MVC has some integration with freemarker and sitemesh. I decided to give both a shot.
Tiles seems to have the most active community.
You can also try a pure velocity implementation.
To sum up, my project ended up reverting back to tiles. Tiles is a robust templating framework, and once you understand it's powers, I will find it hard to find a good replacement. Also, if you are already skilled in apache tiles, I find the benifits of switching frameworks (if any) do not justify the learning curve required to picking up sitemesh/freemarker
http://www.sitemesh.org/overview.html
http://freemarker.sourceforge.net/