My sleeper hit for the best altcoin long term invest ist the WAVES coin. Its almost like ethereum, but much easy to handle for the developers and the users. So if you would buy some now, you will make good gains in future with them. I think one of the altcoins with the most potential. So i can just recommend to everybody to hold some of them in their portfolio. Because it will come a time when you will think why i dont buy more of them in the past?