Both AMP and PWA have benefits, But if your website is mainly focusing on heavy contents then AMP will be perfect. This sounds good for sites that are mainly focusing on heavy contents. But if you have an e-commerce website, you should never ignore PWA that gives your website the feel of a mobile app in a device.
But seeing the current requirement of the market, PWA will be a wise choice. As it helps in improving engagements and experience and not merely on loading contents more faster.