I would say Bitcoin will remain number one in terms of user base and store value because it has a huge community as of now and growing day by day thus I seriously think that it is one of the prime factors. On the other hand, I am not underestimating other coins, each coin has its own philosophy and it might work or won't work down the road but I am confident about Bitcoin and I am also sure that you will find concrete solutions to the current issues like high transaction fees and confirmation time.