It depends on how do you compare them and what do you want to use them for. Ethereum is better than Bitcoin and Bitcoin is better than Ethereum at the same time.
Theyve made several completely different design choices and as with every choice it opens some opportunities and closes dosens of others.
Ethereum is the second largest cryptocurrency in the world behind Bitcoin. It's been actually growing a lot faster than Bitcoin. BTC has grown around 300% in 2017 but ETH is up about 4000%.