Custom eCommerce sites?

For the devs who have built custom e-commerce sites for clients, what was your favorite stack? Would a headless CMS be the best option nowadays?

It’s been a long time building an eCommerce website from the ground-up - especially when lots of platforms provide so much functionality, for little ongoing cost to the client. How do you provide support once it’s built?
After years of working with ye olde Prestashop or WooCommerce platforms, we’ve moved to Shopify. You can still use a decent, new stack and their API is great to tap into!