Shopify is probably better if you want to concentrate on selling and marketing only. All addons are on a monthly subscription so you may be paying around £50-£100 a month including the Shopify fee. Shopify designs are limiting and shops could look generic. No real maintenance cost but you will have to pay monthly subscription fees to Shopify.
The setup and administration here are more complex but this is a good solution if you are planning to grow your website on a budget and want free or very low-cost add-ons. The more add-ons you pick the more you will pay for building and eventually maintenance of the website.
So Which One is Better?
In terms of functionality, they are both good, Woocomerce may have more add-ons to play with. Both have pre-built templates you can get that are optimised for desktop and mobile.
There are apps that can migrate your whole store from Shopify to Woocomerce or vice versa so don’t worry about your current choice as you can migrate for about £100 within an hour.
If you consider cost of maintenance after 1 year WordPress could actually come up cheaper although building the store will cost more.