"Some"
Most of stuff is Atmosphere's. They made only payload, bootloader with their own patcher for KIPs. I don't count homebrew as part of CFW.
https://github.com/Reisyukaku/NX_Sysmodules/
https://github.com/D3fau4/ReiNX-libs/
Everything those...
It outlived everything else. ReiNX stopped getting updates and SXOS died because Nintendo. Equally, lack of reason to make another CFW. Unless Atmosphere dies for some reason, it currently fills the needs for everyone and getting things like Sig...
try dbi installer, heres a guide for it so you can read all the features. it shoud help pinpoint what issues your having. imo, dbi is the best installer
animal crossing new leaf. sometimes the game i mindlessly play the most changes over the years but that one has always been there.
honestly any game i have for my 3DS would probably be just as worthy of the title :-)