Best Practices for Configuring eVars and Event Rules

[Anv_Smo]

For a travel ticket booking site, we collect various data points throughout the user journey, including product type, category, customer details (non-PII), and other details at each step (product view, add to cart, details filled, checkout) before a purchase is made. I am considering three different setups for configuring these rules. 

Could you help me understand the differences and recommend the ideal setup? Can we also use props to make the tracking better for any scenario?
Thank you