I've heard great things about PostHog (YC 20), [1][2] an open-source alternative to Segment. you may find more suggestions in this related thread, too. [3]

hope it helps!

[1]: Direct link - https://posthog.com/

[2]: Launch HN: PostHog (YC W20) - https://news.ycombinator.com/item?id=22376732

[3]: Related thread - https://news.ycombinator.com/item?id=34232908

I love Google analytics - easy to set up and start getting data on where and for how long users are engaging with your product

The one that I'm building, but I'm biased...

https://uxwizz.com