The biggest difference is that those platforms are more data-collection platforms aimed towards developers. userTrack is a complete analytics platform targeted

The biggest difference is that those platforms are more data-collection platforms aimed towards developers. userTrack is a complete analytics platform targeted more towards webmasters and non-techincal users that just want something that works without having to spend time on integrations or creating complex graphs/queries/dashboards. Compared to userTrack, those are more targeted to just storing/displaying analytics and events data. userTrack is aimed more towards qualitative data while providing an easy way to quickly filter to your data and compare different user segments. I have to be honest, I have only heard of posthog before (out of those three), and from what I've seen the target audience and product features don't overlap too much.