What events to chose for Aggregated Event Measurement
If you run ads for your domain, Facebook pre-selected the most important events. Chances are you don’t need to do any modifications.
For e-commerce websites like WooCommerce, you must always select the Purchase Event and give it the highest priority.
You can also select AddToCart, InitiateCheckout, and ViewContent. Give the lowest priority to the ViewContent event, because it tracks the least important action, product page visits.
If you want to optimize for actions not track by Standard Events, create a Custom Conversion first.
Other WordPress websites
For non-ecommerce websites, it really depends on your strategy. If you did Facebook Ads before Aggregated Event Measurement, you probably already have a list of Standard Events or Custom Conversions. Select the ones you used for ad tracking and optimization.