I won't name any names, to avoid problems. One of the conferences is extremely successful. It's a very high-traffic conference. It makes picohits regularly. It has all of the signs of a really thriving conference.
New members post fairly readily.
As soon as they get there, they announce their presence, and generally are welcomed with lots of warm, fuzzy comments. Discussions seem to thrive and find their own course, with relatively little interference from the hosts. The conference practically seems to run itself, and there's a real diversity of voices there. The conference run by the other host has many of the signs of a conference that's in trouble at some organic level. The conference seems dominated by the same posters every day.