Exchanges are not wallet and wallet are not banks so wit's better to hodl your coin yourself and never trust exchanges becaus most of major platform has been hacked at leat one time so you cannot trust them for kep your money in the long term and in some area it's a more bad ideas, reminf you of Bittrex who restrict the account of many people living in some country for month.  Yet there are many negative impact on storing tokens or coin with this  options and that is by getting hacked since some of the exchanges are vulnerable in hacking. So if i were you select a digital wallet that is not always being used and stored your coins there if you are having some intentions to store your coins over a long period of time, but if you really want to keep them on the exchanges do it for a small percentage of your wallet(what you are a willing to really loose).