Altcoins that are worth to hold for 2-3 years are NEO, ETH, WAVES, ADEX, XEM, OMG, STRATIS. These coin has a big potential to grow more with a great developer and team.
Yes, most of the coins above show the good growth rate in between and can be seen often among the top list of the trending big gainers of the coinmarketcap. I've plans of holding Eth, NEM, Waves, TAAS, deep onion and few other coins that are very low in value.