The most recent release (not betas, no dev versions).
For example, when 2024.1.0 drops that’ll be the new :stable.
Which sadly is a point many people miss. For most people the most recent release should be stable. However there’s a limit to what the devs and beta testers can test, and sometimes new bugs appear, or support for ancient firmware gets dropped. Often the problem relates to the hardware people are running HA on (eg running out of RAM).
Personally it’s been a long time since I’ve found any stable release not to be stable for me. That’s not something I could always say - I remember only too well the old days where every release felt like a roll of the dice.