idk, I might consider my self slightly biased because I like the fly.io team, but fly.io has a really simple story for deploying docker images. It'll build them for you, host them, give you secure ssh access, handle connecting to other instances via nice "friendly" names...

I ran several things in Heroku and besides having a point-and-click Postgres product and add-ons Fly can run your app pretty easily. Unless those are the things which you mean that make Heroku super simple.