PHP or Javascript for dynamic plugin?

I'm writing a tool to insert dynamic "Data" on a website. For ease of clarity, imagine I am adding 1 anchor text, and about 100 words with it, but the anchor and text may change at any moment.

I want novice and experienced webmasters to be able to use the tool.

Should I offer the code to be added to the site in PHP? can most websites handle :

<?
echo ("Hello World");
?>

of should I offer it in JavaScript?

can people using WIX or Wordpress add raw code, or do I need to develop plugins for those as well?

I’d say PHp

Javascript has my vote, we got the shaft when php became the language of the web (thanks wordpress).