We've tried a ton of the most popular WP carts out there for ourselves and our clients and can't ever see ourselves looking elsewhere besides WooCommerce now.
Are extensions expensive? Yes - if you expect everything in life to be free. We have gladly paid lots for different extensions for different sites / scenarios. What you get out of the box here is far beyond a basic e-commerce toolset and the extendable architecture is well-designed for customization. Don't get spoiled by an entitlement mindset. We would much rather pay for an extension at the equivalent price of 1-2 developer man-hours than eat 10-20 developer hours ourselves building what we need. Extensions are a benefit. WooCommerce will do a ton out of the box. Add the huge and growing extension library and there are very few scenarios where you'll have to home-grow something yourself.