I can only speak about render.com as I use for a mix of 10 static websites / Go webapps + cloudflare for DNS and caching proxy.

It sounds prosaic but "it just works".

Specifically compared to Digital Ocean Apps (which I used before render):

* the dashboard UI is better designed and faster

* the builds and deployments happen faster

* similar price (to Digital Ocean, much cheaper than Heroku)

* similar capabilities (attached disks, hosted Postgres, hosted redis) but the velocity seems better i.e. render.com seems to implement features faster than DO

You would think that "well designed dashboard that displays instantly" would be a table stakes in an offering like that, but sadly it isn't.

This article compares the two: https://render.com/render-vs-heroku-comparison