3 best altcoins in 2018 it's depends on many factors like project mainnet and team performance but in my views u can check these coins
1 ethereum (you must have ethereum in Ur list there are a lot of development is gonna happen in Ethereum this year they may move to POS form POW )
2 Apex ( most undervalued coin right now , great partnership Great team , and product will be launched in next few months and after that they will move to their own blockchain next year
3 Neo (must have , a lot of icos are coming this year on Neo platform , NOS , NEX are most hyped right now and both are Neo based )

Bonus tip
Sparkster ico, take a look , they are doing great job , scalable secure and best platform to build a Dapp (without knowing coding) , providing cloud services too