I think you should invest both. Bitcoin investment is more stable but profit is not as great as Etherum because Etherum is much cheaper than Bitcoin, which makes Etherum easier to price than bitcoin. But investing in bitcoins is still a very safe channel.
The both of them are very good, but Ethereum is real cheap when compared to Bitcoin, so I might be likely to go for it if Im in a situation where Im left to choose one of the options listed. Bitcoin is good, and is not called the number one for just no reason, but I have been seeing a lot of people talking price is going out of hand and needs correction.