For me much better is to buy both altcoin and bitcoin because the price of bitcoin now is low that you can buy more and hold it until you earn profit and there are still altcoins which are capable of growing up. You just have to do more research to be able to choose the right one. But everyone has their own opinion and the decision is not the same all the time cause sometime it's good to buy BTC but sometime it's better to buy altcoin.