It is very difficult to determine which altcoin is the best.Ethereum is still mineable through the standard mining rigs that are based on GPUs.Besides Ethereum, well-established and rather useful altcoins are Litecoin, Zcash and Monero. They are an easy method of payment and some of them are anonymous. The price of all of the above is very volatile, but steadily rising and there is a bright future ahead of them.