I think more people would be willing to invest in the ETH etf than BTC because they know that bitcoins market cap is already high and there is less room for growth compared to say ETH.
It’s possible for BTC to reach $100K which would be almost double from the day the etfs launched. But something like ETH which has a smaller market cap and decreasing supply, can easily triple or quadruple from here, and this is why many smaller retail investors might want to invest in it instead.
Isn't ETH more unstable, more prone to crashes, more dependent on its founders? Buying bitcoin makes you invest in a unique asset that wasn't made by anyone who can become a target and isn't controlled by anyone. Investing in ETH makes you put your money in one of many similar assets. When someone asks me if they should buy ETH I ask them if they trust Buterin and Lubin enough to put money into their project, especially after Buterin was seen dumping a lot of his own ETH on the market. I think that ETH ETF if it's ever get approved will be popular but not as much as bitcoin. It will be more popular among normal people who want to buy a house with just $10k investment, but companies and countries will stay with BTC.