Very high chances that Ethereum will be the coin of 2018 but Bitcoin's potential can't be ignored. I have high expectations from these two coins. Ripple has also showed a huge rise but I don't think that it will become the coin of 2018.
This year will be the Bitcoin year again, many other alt-coins will follow that progress
and beside Bitcoin, Ethereum have a big chances to rise a lot. Ripple came out of nowhere
and Ripple is on second place now. Ethereum will be second again, and I expect Waves to
make some huge progress too.
There are many good choices, but mine are Bitcoin, Ethereum and Waves. All 3 are good
and perspective projects, and I think that Ethereum and Waves all start their rise very soon.