Those popular coin which is bitcoin and ethereum is good to invest because they have a potential to increase in the future so lot of traders waiting for it. But i suggest bitcoin because bitcoin is the most unpredictable of all coins that have a big pump.
because Bitcoin is the most popular coin at the moment and also the highest transaction coin compared to altcoin so Bitcoin often gives a surprise especially if there is good news then Bitcoin can rise very high because big investors prefer to invest in Bitcoin.
and ETH is the best Altcoin with a very good project so ETH also has good prospects, but unfortunately that ETH depends on Bitcoin, and therefore Bitcoin is still the best.
Not only ETH but all altcoins are depended on bitcoin as they are valued by bitcoin, so bitcoin is the king and if you want to invest then better invest in bitcoin.