Both of the two are effective and fast way of earning money out of bitcoin. Choosing the best between the two is totally subjective depending on its user. You have to look and the different factors that affects how you earn. Compared to mining, for me, I find trading more convenient than mining because it does not require you hardware devices in order to produce the amount you want. Mining also has higher production cost due to the high price of electricity/power to produce it. Trading only requires a small amount of capital.