Shopify setup, GTM tag or subscribing to Shopify events directly?

I have done both across a handful of stores, here is how I decide.

The GTM path wins on operational simplicity: no theme changes at all, one tag that listens to the recommended events in the data layer and maps them to Croct events. If the client already maintains a healthy GTM setup with standard ecommerce events, you are done in an afternoon, and handing the setup over to a marketing team later is painless. A nice detail on this path is that conversion-indicating events like purchase are tracked as conversions too, so goals work out of the box.

Subscribing directly to Shopify events is what I pick when the client's GTM container is a graveyard of stale tags, or when there is no GTM at all. You skip the data layer as a dependency, which means one less thing that can silently break when someone edits the container.

For a standard playbook across clients I would default to GTM and fall back to direct events for the messy containers.

Agree with the above, one extra angle: think about who owns the setup after you leave. The GTM path lives where the client's marketing team already works, the direct path lives in code they may never touch. For a freelancer handing off, that difference matters more than the technical one. The event data ends up in the same place either way, so pick based on maintenance, not capability.