There are so many good coins out there, and everyone is on sale today, so it doesn't really matter which one you pick^^
I personally believe that coins which got an outstanding tech like XRB and IOTA for example have a bright future for 2018, also the coins which don't function as a currency only, better pick these which provide a plattform for developers like Ethereum, Neo, Omisego, Eos, steem, etc

but as I said, it#s only my opinion