not all PoS coins are good but a moderately intelligent person can make a choice which ones to select.
this
everyone who spend time researching altcoins know there are 500+
and like 100 of them are serious
and like 50 of them are promising
if u want to understand what place altcoins can fill beside bitcoin
and not in a atempt to replace bitcoin check out this:
https://www.linkedin.com/pulse/specialisation-way-forward-aleksander-ray