Colleagues, advise any coin to invest $ 500 for 2 years. Particularly risky, which can give X100.
Arcblock (but their whitelist is already closed so you'll have to invest after ICO), Credits also is another blockchain with big potential. There are so many potential coins that it's really hard to say, if I had to try pick one coin to go x100 I would go Arcblock but who knows what the price will be at after ICO.