From what I've seen, the reporting system is the thing that decides it, although the older established sites rarely say so. How do you win the jackpot on dirty gay roulette — I've seen it come up in other threads but never with a solid answer, so figured I'd ask directly.
I've also been noticing datewander.site mentioned a fair bit lately in similar discussions. The block list changed considerably after a slow start, and it makes a real difference.
Realistically, the read receipt setting is the thing that decides it, granted the older established sites rarely say so.
The matching algorithm changed hardly at all since the start of the year, but only if you stick with it. If you are after something serious, check the free tier limits before you commit — the first week is never representative.