Coins like bitcoin are always good to invest in due to it having a high number of investors who are loyal to it so you can be sure that coin will always have value not matter what happens to the market. It is the best pick for the coin for you to hold for the long term. Next is ethereum and then other good altcoins like litecoin and neo.
All these coins are good for long term investment but if you looking to make money in short term trading then better pick cheap potential altcoins. I know this is very tough job because we are not sure when which coin price will increase so concentrate on top 20 altcoins and check experts predictions. right now all altcoins prices are less i will suggest you buy IOSToken.