Wiki's have proven to be quite popular for accessing information whether you are a student or a teacher. I try to avoid them because I question the accuracy of the information contained within them but I will often access a wiki such as Wikipedia to get a background on a topic of interest to me, and then head off to other well established websites or print resources.
They do have one advantage - the fact that you don't need any skills in web publishing and this works fine with many people who more than likely cannot be bothered learning the skills needed to make a website.
The focus is on the presentation of the information itself which is what people want to focus on when presenting their information. I like the fact you can update a wiki at any time from any location on any machine and that it can occur in real time. Groups of students can collaborate together to present information as it is sought and allow for input.
If I had to choose between students creating a web page/site or a wiki for a learning task, I'd favour the wiki. The focus should be on the presentation of the information as opposed to the layout of the site. Students don't need to get into the nitty gritty associated with creating web pages.
However the concern with Wiki's is that other students may "hack" into the wiki and wreck other students work. It might mean backup versions of text may have to be kept just in case the worst happens. Everyday on Wikipedia there are trolls that wreak havoc by changing information to cause trouble. I remember a Wikipedia entry for Ballina several years ago was changed to say that only one person lived there and that they were a "tool". The data and facts for the town had been removed. In fact according to the altered entry it was settled by the Balinese.
As for creating websites, I think they come in more handy where information may have to be presented in a variety of formats such as photographs or video. Websites are more personal as well. I'd use them where the task needs to be done individually and requires multiple formats to be used.
Being a casual teacher, I have found it quite challenging to engage as a member of a professional network because it is harder to meet and get to know other teachers. I feel encouraged by sites such as Ning that allow me to meet other teachers and share my ideas and thoughts on issues affecting the profession but also be informed on the latest happenings in teaching practice.
