a) Solves a real problem b) Relatively easier to understand c) Relatively easier to modify / extend d) Relatively easier to test e) Has seen an evolutionary curve over time
I make my living by writing code for past few years & feel like reaching out to the best folks in the industry for their insights.
It's written in TypeScript and rely heavily on hooks architecture GitHub Repo: https://github.com/refinedev/refine
I tend to focus on things that I'm passionate about and look for reputable and popular open source projects in that area, ie VLC, Audacity, GIMP etc.
This website has several great projects so worth taking a look to see if something catches your eye: https://www.codetriage.com/