Why not both? I suppose im too coward to pick one, ill sail with both bitcoin and ethereum during the 2018. But God knows i like ethereum more

Both for sure will deliver and if you buy it by now surely you will gain a lot, wait for maybe a year or two then the result will be big in terms of gains
btc and eth always find support greater than any other crypto inside the market, and with their popularity investing is really profitable in the long time
hold, so never hesitate to have both coins inside your wallet and forget about it for a while.