I keep an eye on the work censorship.ai does as they are usually at the cutting edge of it: https://geneva.cs.umd.edu/papers/

Tor, Jigsaw's Outline, and V2RayNG are worth keeping tabs on as they're FOSS projects and do much of their development in the open.

Lantern's development whilst it was still open source was fascinating to see as well. Since 2016 (I believe) they stopped doing so out of security concerns: https://twitter.com/adamfisk/status/1316569766832869377