If you wish to hold some coin then use exchange only for during exchange. Just exchange your coin and transfer on your personal wallet that you have controlled. Specially you can use hardware wallet.
Because many exchange hacked buy hacker. Many people loss their capital by hack.
So please don't hold your coin on exchange for long time.
I think that at this point you should not hold coin as well as long term investment at this point, you can see that bitcoin prices are steadily declining in recent days and now fell to $ 5800. The market is very bad signals, bitcoin prices will reduce the price of altcoin drastically and you will be able to lose very heavy if you keep altcoin.