i'm definately a php fan.
here's why:
security: cgi/perl requires a
lot of work to make sure scripts are secure. php generally is a much more
secure platform for simple and complex scripts.
documentation:
php.net. nuff said. if you haven't seen it, go take a look. the function search is the best thing to
happen to programming (sorta). =)
speed: php serves up 10 pages for every 1 page that asp can serve up. i believe it's something like 3 to 1 for cgi/perl. 5 to 1 for jsp if memory
serves me correctly.
cost: it's free! use apache and postgresql and everything is tight! (i, of course, ignore all those that say 'you get what you pay for!' i also believe in free software (yea cs major!).