if I were you I would invest in the most popular crytocurrency at the moment, because they have become popular for a reason, that reason being that they have performed well on the stock market and they have outperformed all other digital currencies available in the world at the moment. Of course they are more expensive and you will also need to read up on all of the most popular ones and choose maybe two or three to invest in. It is not possible to invest in all of the popular ones at the same time, but it is good to diversify among them.