they both have very good popularity but I will still choose the bitcoin that will rule this year and forever because bitcoin is the father of altcoin and bitcoin can rise or fall at any time different from altcoin that always see bitcoin to go up or down
hopefully bitcoin and altcoin at the end of 2018 this price goes up, I expect it all, and come true because after the slump of bitcoin and altcoin can rise again.
I look forward to it.