on revshare, quality. i notice the sites i consider the very best (particularly the member areas) have the highest rebills. now, by quality, i mean respective to the niche. a really good amateur site may not have the best pic and movie quality, but it can hold members forever - especially if the amateur also has a live cam periodically.

of course, if you pay per signup, and have really good upsells, console sales and what have you, the answer might be quantity. if you can pay $30 per signup and still make good money, it's better to have more sites for webmasters to send their traffic to.