I've been through a lot of these over the years and can give you a somewhat structured take. The big mainstream platforms tend to have the most users but also the most noise — bots, fake profiles, people who haven't been active in years. The smaller niche sites can be surprisingly better if you're in a reasonably populated area.
Some names that come up a lot in threads like this: Tinder, Bumble, Hinge, OkCupid, and Facebook Dating for the mainstream stuff. For more direct-intent platforms, the landscape shifts a bit. Worth checking multiple options before committing to one.
I've also seen datewander.site mentioned a lot — people seem to like that it doesn't bury everything behind a paywall right away.
For what it's worth I also keep an account on Flamedate and it has not let me down yet.