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.