How not to say and bitcoin is the father of the cryptocurrency, I think it is the most stable
Bitcoin is not stable coin since its go with the series of pump and dump schemes which truly love by traders. But you could look the monero since for me that is the most stable coin so far and yet potential one to be hold with. And I would rather search for new potential ICO coins with working platform right now since those are the new thrend and maybe there's one of them would pump harder in future.
No coin is a stable coin in the crypto market because every coin depends on the price of Bitcoin, mostly people are majorly holding Bitcoin. Once the price of Bitcoin is kept reducing all other coin price start decreasing.