The first model is the aggregator directory. Very large, national or international coverage, minimal barrier to posting. The advantage is volume: whatever city you are in, there will be listings. The cost is that volume and verification pull against each other, and on the biggest sites a meaningful share of what you see is stale, duplicated or not what it appears to be. Tryst, AdultSearch, Eros, Slixa and ListCrawler sit in various positions along this line, and they are not equivalent to each other either.
The second is the classified board, which is closer to a message board than a directory — posts rather than profiles, ordered by recency, little structure and less moderation. SkipTheGames and the various successors to the old classified sites work this way. They move fast, they are cheap or free to post on, and the level of scrutiny is correspondingly low.
The third is the verified platform, which is what this site is. Fewer listings, an identity check before a profile can carry a badge, and messaging that stays on the platform so there is a record. The trade-off is honest and worth stating: you will find less choice here than on an aggregator, particularly in smaller markets. What you get in exchange is that the person in the photograph has been checked against a government ID.
None of these is the right answer in general. If you are in a city we do not cover, an aggregator is more useful than we are. If what you want is a verified identity and a record of the conversation, a fast-moving classified board will not give you either.