I used this one http://www.emacswiki.org/emacs/php-mode-improved.el for some times. But I switched back to nxhtml as I have to edit too many badly mixed php/html/js/css files these days.
I tried the deboutv one but it sux on emacs (it was created for xemacs) and the development has been dead for some time with some bad bugs left.
You should try the modes available on emacswiki and see if one is good enough for you. If not, well, you know what to do : create your own.