2.ETH
3.LTC
4.BCH
For me this is the best performing altcoin of cryptocurrencies world market that we accumulate.
Especially the BCH o bitcoin cash.
Because bitcoin cash is proven and a good example of an evolved cryptocurrency that is ready for real world use and is able to cater the needs of retailers such as having faster transactions and lower fees by accepting bitcoin cash instead of fiat for payments.
How about XRP?
XRP could be one of best altcoin in 2018 because the XRP has large investor inside the project and if I am not wrong, XRP made approach to the banks but unfortunately, I don't really know and maybe later I will search more about this news. from the list, I think ethereum, ltc, bch, xvg, xmr, bcn, ada, is another best coin in 2018. but it's not close to the other altcoin because I am sure that every altcoin that is a list on coinmarketcap has the same opportunity to be the best coin in 2018.