Hello. A friend wants to start a dating website, she wants me to help her. We still haven't discussed on what platform it'll be developed, but I'm thinking she'll suggest LAMP to save a buck (which is one reason already to chose over ASP.NET already). If the dating website does well, it'll potentially hold a large amount of data (I'm not sure if this would be another reason to consider either ASP.NET or LAMP).

Anyway, I ask this from an ASP.NET developer point of view. I have very little, almost null experience with LAMP, and I don't like it very much either, so if she decides to go with PHP odds are I won't help her. So what would be some good points to bring up when deciding which platform to develop on?

Please be objective, I don't want this to be argumentative or anything, try to stick to facts, not opinions alone.

Thanks!