WooCommerce is the hands-down winner for “must have” transactional engine for any WordPress site that intends to take payments, and even if you do not. The ability to onboard users for free or payment, combined with very tight third party and official extension integration makes this plugin indispensible for anyone. We highly recommend that most site owners use the WooCommerce Stripe gateway (vs. Paypal) to enable modern features without any of the headaches that can come from legacy gateways.