What is the best Linux distribution for old computers?

Updating an Arch system is always a gamble. The problem could be as simple as a package having a bug causing a program to crash on start or it may be something bigger like the WiFi or Bluetooth no longer working. There is also the slight chance the system may not even boot at all after a large update.

If the user does not plan to read the forums weekly/daily or update fairly often, things can go wrong very fast.