So dear friend you want to develop a portal. Apart common search engines feature, web portals may offer other services such as e-mail, news, stock quotes, information from databases and even entertainment content. So as this kind of vast information is provided by portal
The technologies are used in portal development must be best. You can listen that asp.net is more robust than PHP. But don’t forget facebook is made using PHP. So more than language this is important, a team developing your portal, must be expert in development field. So you are right place.