No offense, but nuke sites are really crappy. You'd be better off to fully mod a phpbb site with the ezportal mod instead of using one of those, for security reasons, the phpbb is much more secure than the nuke programs.

But, back to your question, I like uniqueness in a site. If you are using a site that uses themes that you can get from anywhere, make it your own, make it scream your site, what you're about, etc. There is nothing worse than the genericness that sites have become. So many people are getting their own forums nowadays or building portals using a generic portal program and they all look the same. Make your own theme, have features no one else does, but at the same time, make it functional. Awesome looking and easy to use. This will draw more users. If you can write your own mods, then do it. Take your site to the edge and don't be afraid to be different.