Dating Website - Design + AJAX or PHP

This is basically a dating website, with blogs, articles, and local venues/events. We are torn between AJAX and PHP. You make a case for your favorite between the two, and we will decide which best fits our needs. We don't need copywriting, so don't bother applying if you only write. We need web and database developers, who can build a database of users, which will keep track of their likes and dislikes and match them up based upon their answers to a psychological questionnaire. Sort of like eHarmony, but more intriguing, less tedious. As far as the design, we need designers who are minimalist, modern, and playful.