Other than bitcoin? I would go For Monero for its privacy. The transactions made in Monero are completely anonymous and are secure and untraceable. The identity of the sender, reciever is kept private.
Also with a market capital of 3 billion dollars the coin has a potential of having price as $300 per annum within two to three months. You can expect a good amount of worth from the coin.
That is right that bitcoin is the first but if we talk about other altcoin except bitcoin, the i think Etherium has good potential to incrase it price, In fact people are aos putting their investment in etherium, they are confident to invest their money there and that is the reason taht its value is also increasing from time to time. i think Etherium is also a best place to invest your money specially after bitcoin.