as we are in the altcoin marketplace I will not jump in like everyone else to say bitcoin or ethereum, I will suggest you try NEO, while you may feel that Neo is currently pretty expensive and you may have missed the boat on this one, i disagree. Neo has the potential to reach Ethereum's marketcap, and if you had the chance to pick Ethereum up at $150, you would have backed up the truck right? Neo could end up being in the same situation.