GitHub, GitLab, Shopify, and many other sites use Rails. It's still a good choice for certain kinds of sites.

Rails is (and has been) a pleasure to use for fast, easy-ish development if you usually stick to the "Rails style" recommend naming schemes, etc.

If you are trying to adapt an existing project/db that uses some other style, Rails might not be the best tool to use. When you have to supply explicit table/key/route name overrides to everything, you loose a lot of the benefit of using Rails (or any other very-opinionated tool). I loved using rails for multiple projects, but it's worth making sure it's actually a good fit for the project before jumping in.

Pretty sure Stripe and SendGrid are too

So is Lemonade (house insurance app)

Discourse too. But frankly I wish people stop making publicly releasing software as rails app, the resource usage is just insane. I always have to upgrade my server just because of running a single rails app.