Depends. There could be a lot of times in which altcoins became more promising for a while than bitcoin. Those times are when alts are creating more impact than bitcoin. That includes hype, more investors are going in that coin market. And also, a great news might give a big lift on its name. That's why there could be times when alts is more important than bitcoin. Remember sometimes alts from below a dime became more big time than btc when it flew towards a dollar. Buy a bag of it then sell at dollars.