Bitcoin and Ethereum are placed in front of me, and I think they can all be bought. Ethereum chooses fixed investment, and Bitcoin chooses to do the band.
If you choose to hold for the long term, buy Ethereum.
If you want short-term operations, buy Bitcoin.
Finally, make a small prediction here. With the gradual maturity of DeFi applications and the gradual introduction of ETH2.0, the value of ETH will be far more than the current US$400.