Depends on your risk level. If you prefer to be on the safer side and still have huge potential, I would go with the top ERC20 tokens like EOS, VEN, OMG, ICON.
If you have a higher risk level and want a higher return, I would try to find coins with a market cap of around 30m-100m but still ERC20.
I am very bullish on ERC20 since coinbase is adding erc20 support.
but the etherium protocol is created almost all the crypto currency and therefore I give preference to them on this coin. The etheric will not only be promising in 2018, but in the future too.