Best comment management system/plugin to get threaded comments?

[mindKILLER]

The theme I'm currently using doesn't support threaded comments, so I wanted to know what the best comment management system is. Aside from the default threaded comment plugin which doesn't seem to work for me, I've heard of both IntenseDebate and DISQUS, though ID seems to have some problems with importing comments. Do either of these services have any gaping flaws, and are they customizable/simple enough so that they wouldn't discourage casual commenters?

Long story short, I'm looking for a good way to manage my comments and encourage discussion, especially through the use of threaded comments. Any suggestions would be appreciated.