Altcoins with real use case will never disappoint you on the long run ,altcoins like clear foundation ,Hot (hologen) and skycoin will never disappoint because they have a real use case ,if you choose wisely you Wont have anything to worry about.
There are some altcoins that are BIG if you know how to pick them out ,some are backed by popular bigger companies like Microsoft among others.
Do not choose coins because they are mineable or they have implemented POS ,without real use case they will die overtime and lose value.
don't say they will never disappoint like you swear with your life on it. Rather say that they will not disappoint. Apart from the altcoins you just mentioned, there are still many altcoins with real use cases, some are gone while some are still around.