What is your favourite event tracking tool and why?

Years of tracking events and TBH I still haven't found the "golden ticket" but I'll share my experiences up to this point, which covers the last few years.

Mixpanel - $
Lured in by free events, TRACK ALL THE THINGZ. We quickly learned that's not the right approach, and the idea of the "persona" is flawed as it's entirely made of assumptions. We ditched Mixpanel, and began writing job stories instead.

Segment - $
We used to track all kinds of shit. But then GDRP happened and for us it made me reasses what we were tracking, and really questioning if we really needed it. In the end what we needed (day job) was super granular event tracking, meaning events specific to our app. We ditched Segment and saved the cost.

Ahoy - Free
We currently use Ahoy for tracking granular events in our app (day job). It does really well, and Andrew is a stud. https://github.com/ankane/ahoy I have a few dashboards built using the data, feeding into https://chartkick.com/ (another gem by Andrew Kane).

Google Analytics - Free
I currently track events through GA. Yes I use GA, no I don't care that they're a "a big tech company". They are reliable and won't be selling out anytime soon. I use GA together with Google Tag Manager (side gig) and this does pretty well.

Hope this helps.