Developer Edition is essentially Beta with a few changes (which means additional telemetry by default so probably not up your alley):
https://hacks.mozilla.org/2017/04/simplifying-firefox-releas... (edit for better link)
Yeah, I neither want beta nor telemetry...
> Yes, I want Firefox stable. I don't want to run a buggy browser.
? Is the developer edition running the same code as stable?