My own preference is for Steem and Gridcoin, mainly because mining these coins is not an end in itself, but a side benefit of an action that has utility. In the case of Steem you gain coins through communicating, and in the case of Gridcoin through the use of the spare capacity of your computer to generate work on BOINC science projects, such as asteroids@home or the more famous SETI@home.

There are a multitude of cryptocurrency projects whose sole purpose is to mine intangible coins through consuming computer time and electricity , the vast majority of such coins fail. Steem and Gridcoin, however, are produced as a side benefit of a tangible activity. With Steem and Gridcoin you can be certain that your mining efforts will not evaporate in the classic pump and dump strategies seen in the activity of so many coin promoters.