If you ask me best currency for investment then i would like say you BTC and ETH. Because two currency both very old and trusted currency which we can called king and queen. Although don't forget top altcoins market level because there are many top altcoins still in crypto market so you can invest. You should go in coinmarketcap site then check top list currency.
Investing in both tokens that you have mentioned is really a good one but if they are good at trading because as you can see the prices of that tokens, it is really too risky to invest at that high value. But if you tried to study trading, that might give you a lot of profit if you are good at it. If you can study the tools and indicators of trading, I can say that you can gain a bigger profit. There are lots of cryptos that you can invest your money in, just choose those who are promising and the one that you can read the movement of its price.