don't be fooled. PHP can be implemented on IIS/MS and Apache for sure. I'm not up on my reading with Tomcat or JSP, so i can't comment on them.
PHP is a scripting language (i think). It generally isn't as complicated as the object-oriented Java used for JSP, but it isn't as structered either. I personally hate VBScript, ASP, VisualBasic, and most every other proprietarty crap that comes out of that monopoly from richmond...but judging by it's popularity, it could be good.
Overall, i would recommend what you (or your programmers) are most familier with, and can get the most help with.
"There is more than one way to do it."