Only two exchanges? I do not know much about these exchanges, are they reliable? I can see the trading volume is not so much, why?
Both are nothing special, but I bought Oxy from Livecoin and had no issues. However, I don't really reccomend you to keep your coins there, transfer them immediatelly to the Oxy wallet.
You SHOULD transfer them to the Oxy wallet, voting requires more effort then ark, lisk, rise and so on, but it's really worth the effort