In my opinion the altcoin to buy now is Monero, Stellar and Ethereum. These are valuable altcoin for investment and promise to bring a lot of profit for us. Monero offers privacy, all transactions with this altcoin are anonymous. Stellar has great growth rates, I guess that by the end of this year the price of this altcoin will be higher. Ethereum is the queen of the market, it is the foundation of a lot of ICO projects, I believe in the future Ethereum will continue to grow and have a high price.