What to use for a article site/community

I'm planning to start a site where people can add articles which may include pictures on a specific topic, as well as me being able to add my own. I've been using webpress for a blog before, and I like the way the content is managed here, but I believe something different would suit an article site better.

It would also be nice if it included a forum function as well as a member to member messaging function. I'm planning to allow everyone to sign up and post articles easily and place each one in one or more categories. Having the articles seo friendly would be nice as well.


Any tips on what platform would be best suited for this?

 

I would suggest Joomla together with community builder component. I'm working on a community project using Joomla my self now.

 

You can also go with Drupal because:

1) You can set up different content types and define in the backend who should be allowed to post content of those certain types (registered users for example). You can also define if users are allowed to edit their own content or not.

2) Drupal is built extremely SEO friendly. You can define custom "nice" URLs for each page. When you install the Pathauto module SEO URLs are created automatically as soon as a post is saved.