Spain
A tight centre where the evening starts late.
This site is new. Whoever is first here will have a quiet few weeks and will be the reason it is not quiet later.
Madrid keeps an unusual amount of its life inside a small central area, and the evening runs later here than almost anywhere else on this list. Both of those help: the people near you are close enough to meet without planning a week ahead, and the hour at which somebody is free is less of an obstacle.
The site is in English. In Madrid that will suit some people and not others, which is worth saying plainly.
What does not change from city to city: every profile is verified by a live selfie, every message is free, distances are rounded before they are stored, and nothing about anybody is sold to advertisers, because there is no advertising code here to sell it to.
The full list of what gets somebody removed is in the community rules, and what is held about you is in the privacy page.