I also believe Lisk is a solid Altcoin and definitely one of my top 5 altcoins to hold for the long term. I would say Litecoin, Lisk, Ethereum, DASH and Digibyte.
ripple will have huge gains just not a fan of it and I rather invest in something I truly believe in.
My two undervalued coins would be BitBay and ADZcoin. Checkout ADZcoin Road Map and you're see why I think its so undervalued - https://drive.google.com/file/d/0ByjrAqjLGEYnNlZTbTQtVlk1aEE/view?usp=sharing