how can we have to say particularly one best coin. coin demand is based on  market demand. most of the people started to buying the coins then automatically coin value get to increase. so lets we have to start investing in to coins. generally bit coin is the secure for usage. so once to invest in to this coins. bit coin is future  money coin so you have to invest in to this coins. next alt coins and ethereum coins. those are good to invest for earning money.