If you wanna invest in crypto, i think you can invest in BTC and ETH at the same time, investment diversification is better than hold one.
But if you have to choose one from BTC and ETH，i recommend BTC and it is always BTC. BTC can be said to be the pointer of the cryptocurrency market. BTC goes up, the market is bull, the market is down, the market is bear.
Let us see the crypto market, BTC is down about 18.3% in the last month, and ETH is about 35%. It is obviously BTC is more stable than ETH.