I have deliberately chosen a difficult subject today and I will see if I can try to get a handle on it. What I want to start with is a quick indisputable fact. If I had hodled BitCoin or Ethereum when I first invested the difference is quite stark. At the time, one Ethereum was £179 and a BitCoin was £7,400. A quick check, at the time of writing, has shown that Ethereum is valued at £3,311.39 and BitCoin comes in at £90,534.65. Had I invested £1,000 on that day in either currency (aside from spread fees and commission), the results would have been as follows (I think my maths is correct):

While both would have been extremely good investments had I hodled from Day 1 to today, the increase in value of Etherium vs BitCoin would have produced a greater yield; 18 times its value as opposed to twelve times. So on this level Etherium is the clear winner.
Sadly, my other hodled coins are not reproducing anything like this, although I did make some gains with the recent but short lived surge in the price of TEZOs.
One lesson I have learnt is to get back in to Etherium or BitCoin once this bull has stopped running.
But back to my point, to see which is the better coin we need to go beyond the superficial and directly compare the two. I have produced the following table to try to summarise the difference with the help of a bit of further research.

Moving beyond the table and to bring things down to the very nuts and bolts of the matter, BitCoin is ideal if you're seeking a hedge against fiat instability or inflation and with institutional backing and a capped supply which makes it a long-term store of value even though there is less innovation, given less tech risk.
However, Ethereum powers the backbone of decentralized finance and Web3 and is more dynamic, with frequent upgrades and broader use cases. Consequently this results in Ethereum being a higher risk asset that may lead to potentially higher rewards and especially if DeFi and tokenisation continue to scale.
Remember one of the mantras of investment - higher risk = potentially higher rewards - but beware!
Ultimately in deciding which one is better it comes down to your individual wishes and what you are looking for. If you're risk-averse and want a digital asset that behaves like gold, BitCoin is your go-to. If you're betting on the future of decentralized tech and want exposure to innovation, Ethereum offers more upside — but also more volatility.
For me, and for what its worth, I would edge Ethereum, and not so much for the yield difference I presented at the top of the article, but more because it is beyond a repository and serves as I said as the backbone of Web3 and so much is done on the Ethereum network. In fact, again as far as I am concerned, Ethereum will always retain this position unless it is dethroned by another network (such as Optimism), but for now that seems to be unlikely.
This of course is a personal opinion and not investment advice - DYOR
As always, stay safe and well my friends.