My biggest take away from trying to find a Heroku alternative is that Heroku is late to the game of charging for a basic app. Other service might be free, but seem to have some sort of catch--only static, or requires a certain infrastructure, or whatever else--and only Heroku had the unopinionated free tier. And while I haven't used their competitors, I'm skeptical they can match Heroku's interface, CLI, add-on ecosy…
It was the security breach where all of my environment variables were stolen. And the amount of time it took and their level of transparency through it all.