Why just choosing between BTC and ETH? While having some BTC and ETH, which are already accepted in most exchanges and have good reputations is good, its also necessary to get some cryptos that have not gone moon yet. For example, there are cryptos like Genesis vision that will gain more popularity in the future. In addition, even investing in coins like EOS and Tron are good as well. They are going to have a mainnet set up soon and might eventually get listed on Coinbase.