I think it is better you search by yourself why you should buy bitcoin, eth, and xrp. There are too many opinions about the three coins, and we have different things why we choose that coins. But the one must have coin is the only bitcoin because, in the long run, it will give a big profit and if you believe in bitcoin, then my suggestion to you is to buy when is on the low price. It is the same as wit eth and xrp, and if you believe in those coins, you should buy at the low price too.