I prefer on bitcoin because it has a higher value that Ethereum in which you can easily have much money. Particularly bitcoin is not just an easy to get but if you're hard working and patience people it's worth the wait day by day the price of bitcoin is getting higher and higher.
There is a lot of coins who has a potential to give you some good profit in a long run. Bitcoin might be too late to buy nowadays, due to it is price hike. However, if you want to hold Bitcoin in the future, you can buy Ethereum for a long run. Ethereum might hit 1,000$ by 2018. Not pretty sure on that. Which can really give you a good profit whenever you want to exchange your Ethereum to Bitcoin. Sounds pretty interesting.