WordPress vs. DotNetNuke
Should we choose WordPress or DotNetNuke for a website with intuitive navigation and advanced interactive features that include video streaming, image galleries, bi-language support, social media plug-ins, opt-in mail, SEO tools and mobile device friendly formatting?
Since you are making a comparison to WordPress, I'll go ahead and assume you are looking at the Community Edition of DotNetNuke. Since you'll be relying on plugins/extensions to provide you the functionality you are looking for, I think the main question is whether you want to be on the ASP.NET platform or PHP.
It is probably very insignificant, but I do find that most 3rd party apps usually provide a PHP SDK whereas they rarely do for ASP.NET. That of course doesn't mean you can't use the app, it simply means you might have to do more plumbing code to get it going.
I think that either could deliver on what you're asking for, based on what you've provided. Also, they're both open source, and they both have a number of third-party plug-ins so that you can easily customize your website. In the end, I think it would come down to whatever your development team prefers. After all, they're the ones who will be working with the code.