Bitcoin is one the most stable coin. Next to it is Eth. Coins such as XRP, LTC, DASH and RVN could be consider as stable also since the backup community is now have grown and continoully growing. It has gain trust also from the community since investors are seeing more and more demand each day. You can actually check out the Top 10 in coinmarketcao, most of the coin there have reach stable state. Though the price ia not stable, but the standing in Crypto is no denying great.