Currently, Coinbase and Bittrex are no longer secure. Bittrex is having very low volume and is showing signs of release from the management team, they seem to have no recent events. It looks like they are about to let go of it and create something new. As for Coinbase, only Americans should use it, in addition, we should not use it. There have been many cases of account lockout for no reason and no one to support to get back the account. so consider, only Houbi Global or Binance should be selected. Their capitalization is gradually increasing and trade demand is increasing in Chinese exchanges.
I think only Bittrex is insecure because this exchange has very low trading volume and recently a lot of investors have been locked out of their accounts for unknown reasons.
I have not deposited money on this exchange since they were forced KYC users and this exchange has a lot of shitcoin that puts you at a great risk. I am currently using Okex as this is a very fast growing exchange and is among the best exchanges in the crypto market.