Good question and one I've put real thought into. Here's the full picture.
Profile photo quality is the single highest-leverage change you can make. Everything else is secondary.
Things that have genuinely helped me:
- Check reviews from the last six months — older ones go stale fast
- See whether real profiles are visible before any payment is required
- Avoid anything demanding excessive personal info at signup
- Test whether support is reachable before you commit
Currently using Datenest as my main go-to and it's been solid. No major issues, decent activity, enough control over settings.
Take what's useful and leave the rest. Every situation is different.