Comparing Custom Firmwares

Features Stock Atmosphere Kosmos ReinX SXOS Notes
Free x (~$30 USD)
Open Source x
Firmware 9.1.0+ Support x ReiNX have not been updated since 8.1.0 :(
Homebrew Support ? Not all homebrew apps support sxos
Supports Custom Sysmodules
Realtime Cheat Engine
Support Game Modding
Custom Themes need to add a fix for lock screen themes on sxos
Custom boot screens x
FS Patches
ES Patches Atmosphere & Kosmos Sigpatches must be installed manually
Configuration Tools x
Reboot to Payload
Proper Shutdown w/ AutoRCM x x
Button Remapping ? x Using hid-mitm.
Third-party controller support x sys-con or hid-mitm
XCI Loading/Mounting x x x XCIs can be converted to NSP for other CFWs
external hard drive support x x x external drive support is being worked on for atmosphere right now.
Fast on updating code when new switch fw is out x ReiNX have not been updated since 8.1.0 :(
Relevant Guide Here

✓ - Supported

? - Partial or incomplete support

✖ - No Support