If you want to hold 2-3 years? I would pick index coins like. NEO - EOS - ETH - Dragon - Bitcoin. I think you can get pretty far with dividing this between the 5. I am sure you would come back a lot more funded after so long time. The future is in blockchain yes.
Yeah well established coins are your best shot here. Invest in at least the top 2-5 coins in the market if you can hold for that long. Of course bitcoin's a given already so if you can hold alts for that span of time, you surely can hold btc