The both coins have potential to increase but I were to advise you, I'll say you invest in other projects on the Ethereum platform that will yield more profits than the up and down movements these major currencies experience.
If you have enough cash with you it will be very good to invest in both of the cryptocurrency. The reason is that there is possibility of making profit from both ethereum and Bitcoin. One can cover for the other if the other one is not making enough profit.
BOth coins are actually great coins to invest in. I think Ethereum might be better at the moment, though I might be wrong though. But I have been hearing some positive news about Ethereum for some time now.
These kind of decision can only be handled by a single person and that is you alone. Try to find out the best information about the two before taking any move of investment.
I think you should invest on Ethereum since you said the price is going up day by day, and I heard that the best alternative for bitcoin is Ethereum, so I believe it will surely earn you some dollars.
