I think this is going to pretty heavily depend on which machine you have. I am on Luban 4.1.4 since it was the last stable version for the 2.0 machine and 10W laser before the Dual Extruder release starting messing up all sorts of stuff for people, and virtually all changes after 4.4.0 have been related to the J-series, Artisan, and 20W/40W lasers; all unnecessary for me with just added complexity to the software making it less stable. I keep an additional install of the latest version to assist other people with troubleshooting, but I never use it for my own projects.
You can read about all the releases for Luban and the various changes in this forum article: