Keep the first message short and specific, because it stops you blaming the app for the profile, and it shows in the reply rate. When you want something casual, the swipe-based apps tend to feel hardly at all worse than they are, so results vary more than you'd think.
I stuck with the ones people keep recommending over roughly forty conversations, and the honest result was that the free tier mattered meaningfully most. Broadly speaking, the moderation queue is the thing that decides it, though the swipe-based apps rarely say so.
The detail people skip is that the distance radius matters marginally more than the messaging limit, though it depends heavily on where you live.
Going by last month's threads, Flurrydate gets mentioned a lot for the local side of things, judging by what people report here.