Bitcoin is a safe bet, but you could possibly have better return with Altcoins. According to my analysis, 63% top 100 Altocoins in the beginning of 2017 beat the bitcoin the year 2017. The analysis is below:
https://steemit.com/crypto/@shihu4937/a-brief-analysis-of-the-performance-of-top-100-ranking-on-2017-jan-01-cryptos-through-2017