In my option, ETH will increase faster than BTC unless coming lightning to BTC. ETH is really fast and BTC is slow. We will see what will happen
I am a holder of both ethereum and bitcoin, but i think bitcoin is we will still the best this year 2018, and i am confident that on march bitoin is we will start to rise, but for me ethereum is we will remain as the best altcoin.
Bot will manage to do well this year, but ETH would be more advantageous one here. They both should rise, but the rate of rise would be better in ETH, most probably under fair conditions.