Which one of two will have a better ROI in the short, medium and Long term?
Why do I think so: $eth is coupled with a blockchain which has most use cases, most developers and also most support by institutions as I understand.
Etherium as a Long, Medium and Short.
Ethereum will definitely have more ROI than Bitcoin. But Bitcoin halving will drive the price of bitcoin which in turn drives the prices of all the other alt coins.
Bitcoin Halving in general is positive for cryptocurrency space not only Bitcoin.
Ethereum 2.0: Scalable solution with sharding (More adoption coming), he is the winner