maybe a third option!
ETH had its fun this year and got pumped a lot. and usually altcoins only stay active for a limited time before a new altcoin comes along and takes their place.
it is hard to say which one at this point, there are a lot of them with the potential for sure. Waves is an example. even coins like IOTA and also my favorite ByteBall which added smart contracts recently. or maybe a brand new coin with same hypes.
when it comes to altcoins try not to limit yourself to only 1 or 2.
Maybe both of the two because we don't know what the value in the middle of 2018.
As of now I'd rather choose both so that time rolls back i have whats trend for.