If you consider ethereum and litecoin then they are worth buying, they have longterm potential. Never checked ripple before but it looks big so that might be too. If you want more risky ones, nxt and radium looks promising but like I said they are a lot riskier.

The simple problem every altcoin investor facing must be choosing the right altcoins among enormous amount of available options. But no one can be sure about the future hence just the risking is the only way to go with.