What is a better investment, Bitcoin or Ethereum?

Personally, I am in favor of Ethereum now!

Bitcoin and Ethereum are respectively the first and the second cryptographic currency of the market capitalization: on July 11, 2018, the market capitalization of BTC was about $ 108.5 billion, while that of ETH it stood at $ 437.6 billion. The goal of Bitcoin is to become a digital currency, while Ethereum wants to be a decentralized supercomputer.

So strictly speaking, Ethereum and Bitcoin are two separate blockchains with very different use cases. There seems to be no comparison between the two.