Long time or mid-long time is confusing. You don't have to hold for a long, long time, mate. Just know about your profits limit. Like you bought EOS coin by 12$, after few months if EOS goes to 20$ Then what will you do? Hold for more extended time or sell? Crypto coin will not grow all the time; they will go down again and again. That's why I prefer long mid time as you asked in Poll.
For good coins, you may buy EOS, NEO, ADA, STELLER, WAVES, AION, CS, MTC, Ethereum, and LTC. These all coins are outstanding to invest for long or mid-long time. The crypto market can start bully run anytime, so, before late, you need to make a decision. Good Luck.