Been lurking here for a bit but finally decided to post about this.
The account verification process tells you everything. Platforms that skip it are the ones you'll regret spending time on.
The free tiers on most of what I've tried are basically useless — you get just enough to see that real people are there, then hit a wall the second you try to actually message anyone.
If you've got experience with any platforms or approaches that work, drop them below.