public test has everything stable, as far as I know (Ive been working on ASA), experimental has more content but a bit is unreachable by normal gameplay as things have broken over the years.
the old 2015 mod and its plugin are discontinued, public test is the re-release. I know the title is misleading but I never quite got the mod to where I wanted it and still considered it a bit of a test mod.
I am however working on bringing the mod to ASA, much has broken over ark updates but I am about to schedule time per week to work on it.