Allowing User Content vs Keeping it Tight

My niche has a lot of user generated content which isn't currently indexed by Google. I have a growing authority site with dozens of articles focused on specific keywords.

Looking for opinions. Do I

A) Post the user content. Have a stream of new content Google can see, thousands of words daily to show Google I'm a big niche site but risk diluting the existing content?

B) Keep the user content where Google can't see it or use it for backlinks. Only have the keyword specific content on the site.

Hard to figure this one out.

Most affiliate sites don't have this much content but they don't have this much user generated content either.