Think about your top competitor or top 5 rival/competing sites. Now think about your own site.
What makes your site better than theirs? Why should someone join your site before considering joining their site?
If you discover that their site is much better than yours - you should be looking for ways to change that so that your site improves. What sort of ways have your discovered would help your site?
For Christianity Haven, our top competitor is too large to think we could ever match up. Yet, what we have that they don't is a more personable touch with staff that aren't policemen out looking for violations to action. We're more lenient when it comes to members making mistakes on the site.
For Crafter Craze, I think that the Facebook Groups are my biggest competitors. There ARE some individual craft sites but not many active ones that encompass all crafts like my site does.
I'm way too small compared to any other competitor. The gaming niche is very large and would take so much hard work and even so you might be lucky to get to the largest competitor. I do have some other websites that I always go back and forth on to see how they are going and whatnot, they are very much the same gaming sites running IPB forums also. But they are far bigger.
Partly since the person took ownership old Domain name that they been running for 10 years and made a scrip that people love.