For $ 3000 I would buy Ethereum, Litecoin and Cardano. Ethereum is the queen of the market, it has a very large capitalization, just after Bitcoin. Many ICO projects are built on the foundation of Ethereum. Litecoin brings high stability, it is very promising, I believe in future Litecoin will grow. Cardano has a very professional development team, which overcomes Ethereum's many weaknesses.