It's very hard to estimate how much the XRP will be at the end of 2018. All estimates on the internet say between 1$ and 2$. And IOTA is a good currency, but it's far behind XRP. XRP is in the testing phase and IOTA has just been listed this year, so it's a young coin. I would recommend 100$ XRP and 100$ IOTA. IOTA should hold for a longer period than XRP. Upvote please!