I think the ethereum is the best altcoin that make you rich and it will give you a high profit and in future will raise a great results.
500$ is a good amount to invest as you are about to start trading so you should invest in some alt well the best alt is right know in my thinking is ethereum I see that its price will rise soon. Now everyone is going to bitcoin investing buying selling it but no one is very much interested in altcoins so if you invest in altcoins it will give your great profit.