Do you use Google Analytics or rely on your platform’s built-in analytics?
Both. I’ve seen that Analytics is better at reporting traffic, but I’m pretty happy with Shopify’s metrics for most other things (conversion metrics, revenue, etc). For ads I prefer Triple Whale.
It’s been a while since the last time we used GA. We need to upskill with the newest version, but I think the built-in features are sufficient for now 
We use Google Analytics mainly, as we have been used to it and it can bring more feedback while checking.
We use both, and I think many other partners and merchants would say the same.
GA4 is great for leading metrics and gives a solid first impression of how your website or app is performing. From there, you can create customized or built-in reports to dig deeper and get a more complete view of the overall picture I guess.