I would pick Gridcoin (GRC), as it is one of the more interesting coins out there. It's idea is brilliant but also easy to understand for people not in crypto before, see for example this thread that was on the frontpage of reddit: https://www.reddit.com/r/Futurology/comments/4b4drk/a_currency_minted_by_doing_science/t1_d16hch5

It replaces mining with doing research for scientific projects, for example to cure Ebola (http://www.worldcommunitygrid.org/research/oet1/overview.do), fold proteins (https://boinc.bakerlab.org/) or find aliens (http://setiathome.ssl.berkeley.edu/).

I have had GRC and Curecoin too. Now I hold some Foldingcoin