If you want to hold altcoin for the 2-3 years then I suggests you to hold etherum..because nowadays it rate increased too much and in future it will also increase.And I also suggests you to invest in LTC.And nowadays ATC coin is the best for investment. ATC coin is cryptocurrency of India.I also suggest you to invest in it.
Yes they are good candidates or prospects for holding long term like 2-3 years. But is ATC of India a good one? I heard things aren't really good out there for crypto asset holders.
Anyway, holding long term is only excellent for the biggest coins in the market IMO. Others with relatively good prospects, maybe 1 year is the optimum hold duration to maximize benefits.