Nobody can reach consensus on this, seemingly. I started off hanging them but now I squeeze, then flick out the excess water and fluff up the tips gently on a towel, then stand the brush on its flat handle near the window.
The argument seems to be that the amount of residual water is not enough to form a drop and therefore it'll dry just as well if not better by capillary action and evaporation, even if some moisture goes into the breech initially.
I don't claim that this is the definitive answer though, but seems to work for me.