For me, if a coin can replace a bitcoin to pay, that's Etherum. Etherum has all the features of a paid coin that is fast, secure, and anonymously fast, with great support from the community. I think the value of this Etherum in 2018 will continue to grow. Etherum is a coin ranked second after bitcoin in the crypto world.
litecoin can also be a good replacement, as its been a copy of bitcoin and the process will be easier too, likewise with eth much quicker compared to
bitcoin, so if payments is concerned eth and ltc can be an options.