what to use for my web site

Hi everyone, I hope this question isn't stupid!

I'm not a web programmer (yet) but trying hard. I have a simple site
that I created with php4 and mysql. I rewrote it in php5, I rewrote it
again with mysql to xml then converted with xsl. I rewrote it again in
Java. All for the pleasure(!) of learning new stuff. I've dabbled with
Joomla! and quite a bit more with Drupal. I read that a large
percentage of sites were written with Wordpress so I looked briefly at
that.

I met someone who wants to pay me to do a website. It seems to me that
either I should use a content management system or use a php or java
solution, but using a framework. I don't yet have any experience of
frameworks. Now here's my question : having seen what one can do with
Drupal, what are the reasons for NOT using a CMS?

I would like to use Wordpress for the new site, simply for the reason
that it is far more widely used if the statistics are right.
Curiously, I have a filter on CMS on a site proposing contracts and
there are often requirements for Drupal developpers but I've yet to
see one for Joomla! or Wordpress. My own problem with learning to use
a CMS was that it was preventing me from learning PHP!

Any thoughts, advice would be great, thanks.