These are more likely to be off-line agencies who take the time and effort to interview every client .
First piece of advice: if it's free, it's generally free for a reason!
It's worth coming up with a list of criteria you want from a dating site.
Some offer more sophisticated matching than others, based on psychometric techniques often used in recruitment and off-line agencies.
Some, like Introduction Agency and Singles Club RSVP (for example), offer Singles Events - giving you two ways of meeting people. The ABIA website offers comprehensive information on what's on offer from each agency.
For some reason, friends come to me frequently with dating disasters or relationship issues.Category one people will find attractive those agencies where volume is on offer - these will tend to be internet-based solutions.