The coins to HODL are the ones with solid tech, an active dev team and a motivated community.

Privacy coins with solid tech are especially desirable for HODLing, as the demand for them will skyrocket as governments increasingly try to surveil, tax, and control anything crypto related.  When evaluating a privacy coin for long term investment, make sure its tech delivers both network privacy (protection against IP surveillance) as well as transactional anonymity (protection against blockchain analysis).  Covering both of these bases (either in terms of existing technology or in the planning/development stage) is a must for a good privacy coin, yet many privacy coins only cover one but not the other.  Be sure to look at a coin's existing features as well as its roadmap, when evaluating its long term potential.

One such coin is XSPEC; it is a robust privacy coin that is on the cusp of taking the world by storm.  It is (as of yet) a steal at less than $5.

You can find out more about this hidden gem here: http://coinwiki.info/en/SpectreCoin

Come say "hi" to our vibrant and growing community on slack: http://slack.spectreproject.io/