I wouldn't invest in EOS until its issues are properly fixed. There's too much centralization, especially in the arbitration process. Larimer proposed a new constitution to help fix this, but it's going to take quite some time before it becomes adopted by block producers. Right now, EOS is between the $8 - $9 price range, compared to it's All-time-high of $12 per coin. Maybe after everything gets sorted out, prices would start to rise back up again.

But until that happens, I think that it would be best to look out for other altcoins which are usable and promising for long term investing. I'd choose Cardano, NEO, and Ethereum as altcoins to buy and hold for quite a long time. The reason for this, is because such coins are decentralized and have prominent development teams behind them. Their communities are very active and friendly, which makes these coins ideal for holding into the future.

Smart contracts are the future, so I guess that cryptocurrencies which provide such features, will be the ones that are worth buying and holding for a very long time.