I agree completely that the choice of template engine is a matter of taste - Template Toolkit, HTML::Template and the others are nice tools. I've tried most of them, partly because I sometimes teach this stuff and wanted to understand the various pros and cons.

For my own work I've settled on HTML::Mason. Although the installation is typically more involved than several of the others, I don't need to do that often - usually only when I re-install the whole Apache/mod_perl/Mason shebang. I like the the fact that I can create small components with any mixture of html and Perl that I like, and re-use and test them in various pages; the test/debug cycle of these components feels like what I typically need to do with Perl subroutines. I also like the fact that I don't need to learn a different "html scripting" language for use in the HTML; I can use real Perl.