What is the driver of success for any content based website? What makes a great UX for such platforms?

You must make Great content and continue to improve this content according to your audience needs 

There are too many factors to list here but the basic ones are that your content needs to be relevant to the subject you are talking about, the frequency of fresh content should be as frequent as possible as that affects not only users that visit every day but search engines who prefer sites with fresh content. Do not write content for the sake of just having content, as that will take away value and can potentially drive your visitors to other content websites. Content should be of appropriate length, not too short and not too long and should be engaging and a have a human touch and should not look like a PHD research - unless of course if that is the crowd you are targeting.

The content should be straight to the point, concise in content, meets customers needs & always updated. customers would like an easy access medium & creative in form.

The key is having relevent, good, easy to find content.  Thus:

- keep the content fresh and up to date

- make sure the content is relevant to the user, it's something that will increase their consideration of your brand

- make sure the content is easy to find, it's best to index your content for easy search and retrieval