I haven’t used NetlifyCMS - but I can offer feedback regarding Strapi.
I’ve built with Strapi, and the flexibility and ease of use is really good. You’d be able to set up majority of custom options, kind of like how you would with WordPress’ custom post types.
The only caveat that got me with Strapi, is if you need to allow a list of options for the CMS user to select. (ie, lets say you had a layout option with 3 different dropdown values). You’d need to use the Enumeration field to do so, but due to limitations of providing the data (I believe to do with GraphQL), it only has the actual “Values” displayed, not labels, which can get a little confusing for users.
Also keep in mind - coming from WordPress, there’ll be a few gotchyas. You need to manage all the services. Ie, file uploads/storage, mail servers, etc.
I normally use Cloudinary with Strapi to handle image uploads, and you can utilise services like MailGun, or even Netlify Forms for form handling.
Might be worth checking out: https://serverless.css-tricks.com/
Other than that, it’s great.
In terms of performance, as you’d be decoupling the site anyway, I don’t believe the CMS you use will impact performance too much as the data will be retrieved via an API anyway.
Nuxt and Gridsome are both super fast. VuePress is more for smaller applications / blogs.
If you’re looking at using site generators though, Nuxt is capable of doing more, and benefits from server side rendering. With all the subscription based stuff you’re doing, I’d probably choose Nuxt. Both will give you optimal speed rankings. Nuxt’s server side rendering will possibly give you a better SEO ranking, but that’s also debatable and opinionated. Nuxt also comes pre-built with Vue-Meta too.
Hosting - I’ve used Heroku for Strapi, and Netlify for the Vue site. Netlify is free, and allows for builds and continuous deployment with Git integration, so it’s a bit of a no brainer.