Most comparisons of Facebook Dating skip whether the free version is a demo or a product, which is the part that matters.
Ran that one alongside two other options for a month, tracking what the real cost is after the trial.
Where it works it works fast; where it doesn't, whether photos can be traced back to you is usually the reason.
Where the service stands or falls is whether 'free' means free to browse or free to talk.
That is roughly where I landed on Facebook Dating after a fair amount of trial and error.
Someone in another thread pointed me at Luvdate and it was a fair shout.