Yesterday the price of Bitcoin was $9700 and today the price is $8500. Yesterday the price of Ethereum is $200 and today the price is $170. So which coin is prefer to buy?
They both ratio are not the same and you have at the back of your mind that one of them has influence over the other which is Bitcoin. Since bitcoin has price influence over ethereum, I will advise you to buy more if bitcoin over ethereum though investing some percentage of your income in ethereum will not be out of place if you wish, for there is strong probability of you making profit in future.
You should prefer any one of them if you don't have enough funds to capitalize eth or bitcoin investment. Think so many times what would be the best options to choose, because bitcoin remained so strong currency eversince the start of digital currency. Certainly saving each and everytime you bougth have eth and btc with you, we have good future for our assets to provide financial assurance.