Pervasive, easy to use Git repo hosting. I host ongoing personal projects privately and my personal blog (via GitHub Pages).
I also take successful proofs of concept (for example, experimenting with linking AWS Lambda to Heroku Postgres to create a serverless SQL backed web app), and host them as public example repos. These are linked to Dependabot and CircleCI if they have tests so that dependencies can be kept up to date automatically over time and the code using the dependencies can stay fresh over time for example viewers. GitHub