As far as I know BitcoinCash is one of the most popular Bitcoin alternatives I have ever know however there are actually a lot of them but BitcoinCash grows that fast and is also pretty stable when it comes to marketcap. Ethereum, Litecoin, Ripple, Verge and Zcash are just normal Altcoins with different platforms and not a Bitcoin alternatives as they are not Bitcoin's forks except Litecoin which is derived from Bitcoin.