Of course, Bitcoin and Ethereum are the 2 greatest coins to invest in. Which is why it was highly recommended to put investment on those 2 main coins. Bitcoin has much higher value compare to Ethereum but i wont underestimate Ethereum too because both has greater capabilities. But, i also suggest you invest on alt coins.
There are also great alt coins like Eos, Neo, Xrp, Trx, and Xmr, dash and litecoin. You should look into that coins and im pretty sure these coins has great future.