I think ETH is better than Dash and Ripple to invest for future, because ETH have great future ahead, lot of news coins , ICO's are generating in Ethereum platform, and every day more peoples knows about ETH and that technology,I think in next couples of years ETH price will reach above $2000 level, there is good potential for ethereum technology,Ripple and Dash also good investment platform but if you compare with ETH then go ahead invest in ETH