You know both bitcoin and altcoins are good investment because they are not the same in value and uses. They are both important in crypto market. But if you want me to choose of course i will choose bitcoin because this is the leading coin, the most valuable and famous coin,and it is the coin that adopt and accept by  a lot of people all over the world even though other countries does not accept yet the bitcoin. For me bitcoin is the best investment for a long period of time but it need a lot of patience,trust and positive mind.