I think bitcoin will remain the most popular coin in the present and in the foreseeable future .. it is seen from the increasing number of bitcoin users. This may be the effect of very high bitcoin prices.

Moreover, the bitcoin can be said to be the mother of all coin .. so alt coin it is impossible to replace the already famous coin bitcoin around the world. And alt that promise after Bitcoin I think Ethereum because Eth coin according to my system almost the same like bitcoin, even better .. that's just my response ..