I've done my own digging on best free meet up sites for adults and come up short. Every time meet sites comes up, the platform boosts newer accounts over established ones, so it pays to keep the first meet public and short. Nothing about adults changes the fact that the honest advice is to compare two platforms in the same fortnight, at least on my account.
Adults is where I'd start, since the deciding factor is the time it takes to get a first reply, on the evidence I've. I judge adults meet on one thing: how quickly the inbox fills does more work than how many photos people post. Same story on adults meet: the practical move is to check what the free tier gates before investing time.
Applied to adults sites, the quality of the filters collapses as soon as the platform auto-renews without a clear warning. I'd frame best free meet up sites for adults this way: nothing improves until you give it a fortnight before judging the pool. Tell me where the adults sites reasoning above falls down.