Following projects are very promising in 2018 (not all are altcoins):

ETHLend: Lending will be very important and ETH is also the most important altcoin nowadays. Also watch out for the new partnership with Brickblock!
0x: great protocol...really don't know why there is no real pump in 2017...but i'm 99% sure this will moon in 2018
ETH: might reach 2000$ in the end of 2018 (or even more after Casper)
BAT: still undervalued because of its terrible marketing but it will shine soon
REQ: There are sooo many payment networks out there but I believe in this one...good possibility to go to 1$ in the end of 2018
SNM: sleeping giant which will overcome GNT
PPP: In my opinion its better than PPT
Ripple: a little bit unsure about that one but a little pump is possible