A good medium term investment will be both options. Now excellent prices for buying, so you can buy. The market has long been in a downtrend, so in the medium term, you can count on its rise. If you plan to invest in crypto currency, bitcoin will be an excellent solution. As for the altcoins, they will also grow after bitcoin, the main thing is to approach the choice of coins intelligently. It is best to choose the coins from the top 30.
I think that at this point you should not buy or invest in altcoin and altcoin, you can see that bitcoin and altcoin prices are constantly decreasing in the past few days, so I believe that this time you should just head short term and day trading. The market is in the downtrend stage so the bitcoin price will probably drop sharply in the near future and consequently the altcoin price will drop accordingly, you invest at the moment the risk will be very high.