Both coins are solid investments, but which will you choose BTC @ 20k$ (just like what happened in the last quarter of 2017) or ETh @ 2,500$?
of course bitcoin is more promising to grow compared to ethereum or other altcoin. the most logical fact is, bitcoin is very binding to the market. until the rise and fall of bitcoin is very influential on other crypto. because this is the bitcoin always the king of all crypto.