Suppose if this question had been asked three years ago, when ETH was launched and had started to grow, what would have been the answer to the question? Of course the one with great technological advancement leads. Today after three year, Bitcoin still leads in the front and it is an inevitable and undeniable truth that it is the best coin for future however we do not know about the next advances thing. The fastest race has not been run yet so we can expect something mush better than Bitcoin as well.