We own a portfolio of sites, some processing tens of thousands of orders per month, others in the thousands, some of the newer ones in the hundreds. All of them are on Shopify or Shopify Plus.
If you sign up for Shopify Payments the payment fees are waived on all payment methods - well they are for us anyway. Plus the Shopify Payments UX is much more favourable than being taken off site with Sage Pay or Worldpay for example.
Possibly the biggest advantage of Shopify is it’s a hosted solution. You don’t need a dev on hand to constantly patch vulnerabilities and you don’t need to maintain your own server or hosting - like you would on Wordpress and other CMS.
Wordpress is essentially a blogging CMS and really isn’t/wasn’t designed for ecommerce. Yes WooCommerce does a job, but it’s not in the same league as Shopify.
Other hosted solutions like Visualsoft are also possible, but I think they’d come in way more expensive than Shopify.
Shopify also has the benefit of the App Store. There’s so many good apps in there that save the time and hassle involved with carrying out tweaks or adding functionality from scratch.
Personally I’d go with the basic Shopify plan and see how you get on.