It is difficult to answer this question unambiguously. Because no one knows what the future holds. After all, this year no one knew how much the market will fall down. So to judge the most promising coins, which surpass BTC I don't see the point. I still believe that the first place has always been and will remain for BTC. Then there is ETH, and only then all the rest of the coins. Therefore, if there is extra money, then invest in these coins. If capital is not enough, then invest in NEO, ADA, EOS or XRP.
I also think it has no point to discuss which coin will be Nr. 1 vs Nr. 2 in xyz months/years. I personally think Ethereum has stronger fundamentals but history has shown that branding is often more relevant than tech. I also think next to BTC and ETH the next gen blockchains NEO, EOS and ADA are a very solid portfolio with minimal risk and still overall string growth persoectives. Better be a bit diversified than betting on a single horse.