There are many good options already mentioned here, but I noticed no one has brought up Tribe eCommerce - and it definitely deserves a mention.

Yes, Shopify is a big player in the eCommerce industry. It’s popular for many reasons such as fast setup, lots of integrations, and a solid app ecosystem. But if you're looking for complete flexibility, customization, and full control & ownership, Shopify couldn't fit. You're tied to monthly fees, app dependencies, and restricted backend access.

That’s where Tribe eCommerce shines as a strong alternative of Shopify.

Tribe is a self-hosted, 100% white-label eCommerce platform built for businesses that want full control over their online store from front-end design to backend logic. You get the source code, host it on your own server, and there are no recurring fees, just a one-time license fee require. It's perfect if you’re building a niche online store, or want the freedom to customize without boundaries.

Tribe eCommerce software is built for modern commerce, it ensures a smooth mobile experience and supports growing businesses with modular, scalable architecture.

Tribe eCommerce is hands down the best Shopify alternative to build a truly customizable online store within short span of time. It's ideal for businesses that want to move beyond the limitations of hosted platforms and take complete control of their eCommerce journey.

Click here to more: https://www.tribe-ecommerce.com/blog/best-shopify-alternative-tribe-ecommerce/

My Recommendation:
If you want the full control, scalability, complete ownership,and looking for long term growth, go with Tribe (https://www.tribe-ecommerce.com/) for a quick start and scale your business fast.