Not so long ago I invested in the money to Ethereum and gained a little from it. It was in those times when countries were not yet interested in virtual currencies.
I like ethereum better, i think it is a more complete solution to the bitcoin proposal. So if i were to choose between two coins regardless its acceptance and market cap i would go for ethereum.
Depends on what your doing, personally, if you are just starting out with mining now, I think you've left it to late.
But, if you are trading, then you've got a lot of options and ETH like many others 'can' be good. Some days, I can make a decent earn, but mostly it's sheer dumb luck. I say that because crypto is just so damn volatile, it's downright scary in the peaks and dives it can take in just 15mins. That's where you make the money though, if you see a dip, buy in, sell when you think you've hit a perceived peak. I'm not suggesting you do that though, best to start watching the markets daily, seeing trends etc. Then, dive in if you think it's the right thing for you.
Of course, you should only invest what you can afford to lose, It's a fickle and fast market.