It depends upon how much you have to invest in, Let me put two scenarios in front of you. If you have big investment figure like $ 10000 or more than I suggest you to invest in best Altcoin which is Ethereum. Ethereum is very promising altcoin and it's going to be highly demanded in future as many ICOs launch using Ethereum blockchain and it is highly expected that Ethereum will reach $ 1500 in 2018. Other scenario is you have low budget to invest like maybe $ 1000 or less so I think you should consider investing in Minexcoin, It had recently made a huge jump from $ 3 to $ 70 in last month and it is expected that it will repeat it again. I think it's much suitable to buy, Choose your self. Best of luck.