I looked at Dokku and Flynn for personal (single host) projects and find both to be too complicated for my needs. I generally prefer deploying Docker containers over Heroku buildpacks.

I ended up just running a single Digital Ocean droplet with Traefik as a loadbalancer/entry point, and then running each of my projects with docker-compose. (And building each project with Docker)

With Traefik I can set up reverse proxying for each project just by adding a few labels to its docker containers, and Traefik manages LetsEncrypt for me.