I think it is not necessary to choose one single coin. It is necessary to distribute investments between several coins, but also you have to monitor the movement of the market and adjust your investments. At the moment, ETH shows good growth.
yes I agree with you, you should invest in some coins that you believe provide benefits, the top 10 in CMC can be taken into consideration to invest, for now ETH and LTC have good growth, in August LTC will be halving so I think both of these coins will growing up until next month same as bitcoin, don't miss it to take advantage of getting the benefits.